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Side Rear Under Spoiler Kit

Aero styling for the rear bumper and designed to work with STI's other aero parts. When used together as a package the overall aero performance is increased.

Usually ships within 2 to 3 days

Manufacturer: STI


  • WRX STI MY2015+
  • WRX MY2015+
  • JDM WRX S4 MY2015+

Can you briefly explain aerodynamic lift, downforce, and drag as it affects a car? Aerodynamic lift occurs when air pressures acting on the bottom side of the vehicle (or component) are higher than that acting on the top side resulting in a net upward force. Downforce is negative lift. The lift forces add or subtract from the forces affecting the tire contact patches and therefore will alter available traction. The distribution of lift will affect the handling balance if the effect on the front and rear wheels is not equal. Drag is a measure of the air resistance acting on the vehicle. Lift, downforce, and drag forces increase exponentially with speed.

Does this really provide a noticeable performance advantage? The aerodynamic effects amount to a couple percentage points. The benefits will only be noticeable at very high speeds and therefore in a street application it should be considered purely as a style enhancement. For a dedicated track racing application a front splitter with a large surface is preferred if the regulations allow.