IMPREZA WRX STI
2004 SubaruIntake upgrades help the engine inhale more freely and provide a lot of bang for the buck. Less restrictive air filters and a tuned intake manifold allow more air into the engine, making more power.
Improves torque. Only available on naturally aspirated engines.
Fuel system upgrades can yield big power increases. They provide more efficient fuel flow, more precise timing, the ability to use higher-octane fuel, and they extract more power from the fuel you use. These changes can be as simple as installing a custom Engine Control Unit (ECU) chip or as complex as changing the fuel pump and tank, injectors, and fuel hoses.
Ignition upgrades help the engine burn fuel more efficiently to produce more power. Adding better coils, spark plugs, and ignition wiring can make a significant difference in engine power and car performance.
Exhaust system upgrades such as improved headers, mufflers, bypasses, and large-bore tubing provide extra power for a relatively low cost. They let the engine exhale more freely and create more power by reducing back pressure and extracting exhaust gases more efficiently. These upgrades also make an audible difference.
Upgraded cams let your engine breathe more freely and rev to higher RPM, producing more torque and power. The net result is a higher redline and more power in the high-RPM range.
Valves allow the air and fuel mixture to enter and exit the engine. Upgrading these allows for more air flow increasing power.
Displacement upgrades make the engine more durable and less damage-prone. They can also reduce friction/inertia and increase displacement/compression to make the engine more powerful and responsive.
Upgrading pistons allows for high-compression ratios increasing power.
A turbocharger provides a major power increase by using exhaust gases to spin a turbine, which compresses the air-fuel mixture and forces it into the engine at more than atmospheric pressure. The result is more energy per stroke, which makes more power. These upgrades also make an audible difference.
A supercharger is an air pump driven by a belt connected to the engine's crankshaft. It provides a major power increase by compressing the air-fuel mixture and forcing it into the engine at more than atmospheric pressure. The result is more energy per stroke, which makes more power. These upgrades also make an audible difference. A centrifugal supercharger forces induction with an impeller fan, similar to a turbocharger. Centrifugal superchargers build boost in proportion to RPM and noticeably improve top-end power. While centrifugal superchargers produce boost more efficiently than positive-displacement superchargers, all of that power is concentrated at the top of the RPM band.
A supercharger is an air pump driven by a belt connected to the engine's crankshaft. It provides a major power increase by compressing the air-fuel mixture and forcing it into the engine at more than atmospheric pressure. The result is more energy per stroke, which makes more power. These upgrades also make an audible difference. Positive-displacement superchargers produce low boost across the RPM range and a noticeable improvement in low-end and mid-range torque. While positive-displacement superchargers produce boost more evenly than centrifugal superchargers, they are less efficient.
A turbocharger provides a major power increase by using exhaust gases to spin a turbine which compresses the air-fuel mixture and forces it into the engine at more than atmospheric pressure. The result is more energy per stroke, which makes more power. These upgrades also make an audible difference. Two are usually better!
An intercooler is a small radiator that cools the hot air from a turbocharger or supercharger before it is forced into the engine. This makes the air-fuel mixture cooler, and therefore more dense, packing more energy per stroke.
Adding oil cooling keeps the engine's oil at the correct temperature, aiding efficiency and increasing power.
For a stock car, the rotating mass of the flywheel smoothes and steadies the rotation of the driveshaft, but it decreases throttle response and acceleration. Upgrading to a lighter-weight flywheel allows the engine to respond to the throttle more quickly and increase RPM faster, providing better acceleration.
Brakes are an important part of the total performance picture. To be competitive, your car's brake performance must match its power and handling. Leading the pack at the end of a straight won't help if you can't slow down fast enough to make the next turn. These upgrades increase braking power and decrease brake fade due to excessive heat.
Springs and dampers can make a big difference in your car's handling by maintaining optimum ride height and tire contact.
Front anti-roll bars (also called anti-sway bars) provide extra stability when cornering. When you turn left or right, the car body tends to roll in the opposite direction. By tying the left and right sides of the suspension together, anti-sway bars make the car ride more level and keep one side from rolling or swaying more than the other.
Rear anti-roll bars (also called anti-sway bars) provide extra stability when cornering. When you turn left or right the car body tends to roll in the opposite direction. By tying the left and right sides of the suspension together, anti-sway bars make the car ride more level, keeping one side from rolling or swaying more than the other.
Chassis reinforcements stiffen the shell of the car, reducing flex when cornering, which in turn aid the suspension in keeping the maximum amount of tire on the road.
A lighter car accelerates and handles better than a heavier one. Reducing weight by removing nonessential materials or replacing stock parts with lighter ones pays off on the track.
The clutch is the vital link between the engine and the transmission. Upgrades increase the clutch's ability to handle the extra torque of a racing engine without damage.
The transmission transmits you car's power from the engine to the drive wheels. Transmission upgrades can make shifts quicker and more efficient, reduce friction and power loss, and provide better durability. These upgrades also make an audible difference.
You can improve throttle response and acceleration by decreasing the weight and inertia of driveline components, especially the driveshaft itself.
The differential allows the tires on each side of the car to turn at different rates because the inside tire travels a shorter distance around a turn than the outside tire. A limited-slip differential locks at a preset point to limit this difference in rotational speed, providing maximum traction under acceleration and/or deceleration.
Upgrading to tires with a softer, more aggressive compound increases traction and improves the tires ability to maintain traction despite high heat, but also increases wear. The harder compound used in stock tires sacrifices grip to increase wear. These upgrades also make an audible difference.
In general, more rubber on the road means better traction and performance. Upgrading to larger, wider tires provides more contact area and thus more traction. You can use wider normal-profile tires to improve traction by enlarging the tires contact patch on the pavement. Or you can choose larger rims and low-profile tires with shorter, more rigid sidewalls. These tires are less prone to deforming as acceleration and cornering forces increase. This improves traction by maintaining tread contact with the pavement.
In general, more rubber on the road means better traction and performance. Upgrading to larger, wider tires provides more contact area and thus more traction. You can use wider normal-profile tires to improve traction by enlarging the tires contact patch on the pavement. Or you can choose larger rims and low-profile tires with shorter, more rigid sidewalls. These tires are less prone to deforming as acceleration and cornering forces increase. This improves traction by maintaining tread contact with the pavement.
Choose larger rims and low-profile tires with shorter, more rigid sidewalls. These tires are less prone to deforming as acceleration and cornering forces increase. This improves traction by maintaining tread contact with the pavement.
Choose larger rims and low-profile tires with shorter, more rigid sidewalls. These tires are less prone to deforming as acceleration and cornering forces increase. This improves traction by maintaining tread contact with the pavement.
A wider spacing between the front tires can provide additional stability under lateral G force.
A wider spacing between the rear tires can provide additional stability under lateral G force.
Increase or decrease the front wheel size.
Increase or decrease the rear wheel size.
You can upgrade your front bumper to increase the load over the front wheels by increasing downforce. These upgrades allow higher cornering speeds. Note that Race upgrades make downforce adjustable.
Upgrading the rear wing on your car increases the load over the rear wheels by generating downforce to allow higher cornering speeds. Note that Race upgrades make downforce adjustable.
Rear bumper upgrades improve handling by decreasing lift at high speeds. The Level 3 upgrade also increases the load over the rear wheels by adding adjustable downforce. These changes allow higher cornering speeds.
Adding modified side skirts reduces weight and drag to improve overall performance.
Upgrading to a lighter-weight hood reduces overall weight and balance to improve performance.
You can swap in a new engine to get more power and possibly reduced weight, but every engine has its own upgrade path. Any upgrades on your current engine will not apply to the new engine. As a result, your car's power may actually decrease with an engine swap. Even with a new, more powerful engine, you may not win races. Winning performance calls for a balance between power and handling. An engine swap also makes an audible difference.
You can swap an entirely new drivetrain into your car to get different driving characteristics and possibly reduced weight, but every drivetrain has its own upgrade path. Any upgrades on your current drivetrain will not apply to the new drivetrain. As a result, your car's handling may actually decrease with a drivetrain swap. Even with an upgraded drivetrain, you may not win races. Winning performance calls for a balance between power and handling.
You can significantly alter your car's body work and stance for a bold new look, different driving characteristics, and possibly reduced weight. Some upgrades on your car's current body will not apply to the new body kit. As a result, your car's handling may actually decrease. Even with a body kit, you may not win races. Winning performance calls for a balance between power and handling.
Tires
The optimal pressure for tyres depends on the tyre compound you are using. The intention of tyre pressure tuning is to maximise the contact patch of the tyres without them overheating or becoming unresponsive. Lower pressure increases the contact patch, but too low reduces responsiveness and can cause the tyres to overheat. Higher pressures can increase responsiveness, but reduce tyre temperature and can lead to a sudden loss of grip.
The optimal pressure for tyres depends on the tyre compound you are using. The intention of tyre pressure tuning is to maximise the contact patch of the tyres without them overheating or becoming unresponsive. Lower pressure increases the contact patch, but too low reduces responsiveness and can cause the tyres to overheat. Higher pressures can increase responsiveness, but reduce tyre temperature and can lead to a sudden loss of grip.
Gearing
Adjusting the final drive ratio affects acceleration and top speed by scaling the ratios of all the gears in the gearbox. The higher your final drive, the shorter your gear ratios will be, which can lead to improved acceleration at the cost of reduced top speed or topping out in your final gear. Lowering your final drive can improve top speed but can reduce acceleration.
Adjusting individual gear ratios affects acceleration and top speed. A higher ratio makes for quicker acceleration. A lower ratio gives a higher top speed. Choosing the right ratios matches your engine's power and torque to the circuit on which you're racing.
Adjusting individual gear ratios affects acceleration and top speed. A higher ratio makes for quicker acceleration. A lower ratio gives a higher top speed. Choosing the right ratios matches your engine's power and torque to the circuit on which you're racing.
Adjusting individual gear ratios affects acceleration and top speed. A higher ratio makes for quicker acceleration. A lower ratio gives a higher top speed. Choosing the right ratios matches your engine's power and torque to the circuit on which you're racing.
Adjusting individual gear ratios affects acceleration and top speed. A higher ratio makes for quicker acceleration. A lower ratio gives a higher top speed. Choosing the right ratios matches your engine's power and torque to the circuit on which you're racing.
Adjusting individual gear ratios affects acceleration and top speed. A higher ratio makes for quicker acceleration. A lower ratio gives a higher top speed. Choosing the right ratios matches your engine's power and torque to the circuit on which you're racing.
Adjusting individual gear ratios affects acceleration and top speed. A higher ratio makes for quicker acceleration. A lower ratio gives a higher top speed. Choosing the right ratios matches your engine's power and torque to the circuit on which you're racing.
Alignment
Adjusting camber (the top-to-bottom angle of the tyres) affects your car's grip whether you are driving in a straight line or cornering. Negative camber results in the tops of the tyres leaning inward, maximising the contact patch during cornering. Too much negative camber can decrease straight line braking and acceleration efficiency, as negative camber reduces the contact patch when driving straight. Positive camber results in the tops of the tyres leaning outward which can make the car unstable, as it reduces the contact patch during cornering.
Adjusting camber (the top-to-bottom angle of the tyres) affects your car's grip whether you are driving in a straight line or cornering. Negative camber results in the tops of the tyres leaning inward, maximising the contact patch during cornering. Too much negative camber can decrease straight line braking and acceleration efficiency, as negative camber reduces the contact patch when driving straight. Positive camber results in the tops of the tyres leaning outward which can make the car unstable, as it reduces the contact patch during cornering.
Adjust toe (the inward or outward angle of the wheels) to sharpen turn-in response (the transition between driving straight ahead and turning). Toe-in brings the fronts of the tyres closer together than the backs. This can increase stability at the cost of turn-in response. Toe-out brings the backs of the tyres closer together than the fronts. This can increases turn-in response at the cost of stability.
Adjust toe (the inward or outward angle of the wheels) to sharpen turn-in response (the transition between driving straight ahead and turning). Toe-in brings the fronts of the tyres closer together than the backs. This can increase stability at the cost of turn-in response. Toe-out brings the backs of the tyres closer together than the fronts. This can increases turn-in response at the cost of stability.
Adjusting caster (the forward or rearward angle of the steering axis) enhances straight-line stability. With positive caster, the steering axis is inclined rearward. Because negative camber increases as the suspension compresses and/or the tyres move through steering lock, increasing positive caster lets you run less negative camber. This results in a straight-up tyre while driving straight ahead (good for acceleration and braking) but provides a desirable amount of negative camber while cornering.
Anti-roll bars
Anti-roll bars control unwanted body movement and balance understeer versus oversteer in steady-state cornering. The balance of front and rear antiroll stiffness affects the balance between understeer and oversteer. To reduce understeer, you can soften the front bar, stiffen the rear one, or a combination of both; to reduce oversteer, you can soften the rear bar, stiffen the front one or a combination of both.
Anti-roll bars control unwanted body movement and balance understeer versus oversteer in steady-state cornering. The balance of front and rear antiroll stiffness affects the balance between understeer and oversteer. To reduce understeer, you can soften the front bar, stiffen the rear one, or a combination of both; to reduce oversteer, you can soften the rear bar, stiffen the front one or a combination of both.
Springs
Spring stiffness controls how the car's weight is transferred under acceleration, braking, and cornering. Stiffer front springs transfer more weight, but too much can cause the tyres to lose traction under heavy load. Softening the front springs in relation to the rear increases front grip and reduces understeer, but too much can cause the car to bottom out under heavy braking. Increasing the front springs' stiffness in relation to the rear can reduce oversteer, but too much can cause the car to understeer.
Spring stiffness controls how the car's weight is transferred under acceleration, braking, and cornering. Stiffer front springs transfer more weight, but too much can cause the tyres to lose traction under heavy load. Softening the front springs in relation to the rear increases front grip and reduces understeer, but too much can cause the car to bottom out under heavy braking. Increasing the front springs' stiffness in relation to the rear can reduce oversteer, but too much can cause the car to understeer.
Ride height determines your car's ground clearance and centre of gravity. Lowering ride height lowers the centre of gravity, which improves cornering, but lowering it too far can cause bottoming out and sudden loss of control. Generally, you should lower your ride height as much as possible without bottoming out.
Ride height determines your car's ground clearance and centre of gravity. Lowering ride height lowers the centre of gravity, which improves cornering, but lowering it too far can cause bottoming out and sudden loss of control. Generally, you should lower your ride height as much as possible without bottoming out.
Damping
Tuning your car's damping improves handling by increasing grip. Bump damping controls the rate of compression as the suspension goes up into the wheel wells. Increasing front bump damping stiffness can increase transitional understeer, but excessive bump damping can make a car unstable over rough surfaces. Decreasing front bump damping stiffness can increase transitional oversteer.
Tuning your car's damping improves handling by increasing grip. Bump damping controls the rate of compression as the suspension goes up into the wheel wells. Increasing front bump damping stiffness can increase transitional understeer, but excessive bump damping can make a car unstable over rough surfaces. Decreasing front bump damping stiffness can increase transitional oversteer.
Tuning your car's damping improves handling by increasing grip. Bump damping controls the rate of compression as the suspension goes up into the wheel wells. Increasing front bump damping stiffness can increase transitional understeer, but excessive bump damping can make a car unstable over rough surfaces. Decreasing front bump damping stiffness can increase transitional oversteer.
Tuning your car's damping improves handling by increasing grip. Bump damping controls the rate of compression as the suspension goes up into the wheel wells. Increasing front bump damping stiffness can increase transitional understeer, but excessive bump damping can make a car unstable over rough surfaces. Decreasing front bump damping stiffness can increase transitional oversteer.
Aero
Increased downforce keeps your car in better contact with the road, heats up the tyres more quickly, and improves handling at speed. Efficiency refers to the amount of drag the car creates. The higher the value, the more efficient the car is, which means the less drag it creates. Increasing downforce will increase the amount of drag being produced. Balance refers to the aerodynamic balance of the car. The greater the difference between front and rear downforce, the greater the characteristics of the car changes. The lower your Balance value is, the more understeer the car will exhibit, and the greater the value, the more oversteer.
Increased downforce keeps your car in better contact with the road, heats up the tyres more quickly, and improves handling at speed. Efficiency refers to the amount of drag the car creates. The higher the value, the more efficient the car is, which means the less drag it creates. Increasing downforce will increase the amount of drag being produced. Balance refers to the aerodynamic balance of the car. The greater the difference between front and rear downforce, the greater the characteristics of the car changes. The lower your Balance value is, the more understeer the car will exhibit, and the greater the value, the more oversteer.
Braking
Brake balance affects the distribution of the braking force. This in turn affects braking distance and understeer/oversteer balance while braking. Adjusting brake balance rearward increases oversteer under braking, while adjusting brake balance forward increases understeer and improves stability, but it can also lead to excessive understeer when braking.
Brake pressure affects the amount of force generated, based on how much braking you apply. Reducing total brake pressure increases the amount of pedal travel to generate significant braking force. However, if you reduce it too much, the car will be unable to decelerate effectively. Increasing brake pressure reduces the amount of pedal travel required to generarate significant braking force, but increasing too much will lead to the brakes locking up immediately.
Differential
The Accel differential setting adjusts how much difference in wheel rotation is required to lock the differential under acceleration. Increasing the Accel setting makes the differential lock more quickly under acceleration. Reducing the Accel setting makes the differential lock more slowly. On front differentials, reducing the Accel setting can reduce understeer, but reducing it too much can make the car unresponsive.
The Decel differential setting adjusts how much difference in wheel rotation is required to lock the differential under deceleration. Increasing the Decel setting makes the differential lock more quickly under deceleration, but excessive differential locking can impair handling. Decreasing the front Decel setting can reduce lift off oversteer, but increase the likelihood of locking the front brakes (without ABS enabled).
The Accel differential setting adjusts how much difference in wheel rotation is required to lock the differential under acceleration. Increasing the Accel setting makes the differential lock more quickly under acceleration. Reducing the Accel setting makes the differential lock more slowly. On front differentials, reducing the Accel setting can reduce understeer, but reducing it too much can make the car unresponsive.
The Decel differential setting adjusts how much difference in wheel rotation is required to lock the differential under deceleration. Increasing the Decel setting makes the differential lock more quickly under deceleration, but excessive differential locking can impair handling. Decreasing the front Decel setting can reduce lift off oversteer, but increase the likelihood of locking the front brakes (without ABS enabled).
A centre differential controls the relative distribution of drive torque between the front and rear axles in all-wheel-drive cars. Increasing torque to the rear directs a higher proportion of the power to the rear wheels, increasing responsiveness and oversteer. Increasing the rear torque split too much can lead to wheelspin and too much oversteer. Increasing torque to the front reduces throttle oversteer more like a front-wheel-drive car, making the car more stable but increasing too much can cause significant understeer.