Flat 6 Motorsports Over Axle Pipes - OAP (718 GT4 / Spyder / GTS 4.0)


Designed to Fit

  • 2020+ Porsche Cayman GT4 / GTS 4.0 (718)
  • 2020+ Porsche Boxster Spyder / GTS 4.0 (718)

Note - These are designed for North American market vehicles. 

Product Details

The Flat 6 Motorsports Over Axle Pipes (OAPs) for the 718 GT4 and also compatible with all 4.0L 718s, provide a high flow and smoothed exhaust flow design. These are a direct factory replacement and bolt on solution, making it an easy to do install for most skill levels. 

The Flat 6 Motorsports over axle exhaust pipes are engineered to provide optimal flow and maximum performance. Our GT4 over axle pipes are made from T-304 Stainless Steel and feature a proprietary heat-shielding technology to insulate heat inside of the piping. This dramatically reduces heat transfer to key components like brake rear brake lines, axles and suspension. The OAPs are meticulously TIG welded for a high quality finish and lifelong durability. 

See also the Soul Performance Competition Over Axle Pipes.


    • Direct Factory Replacement
    • Significant Exhaust Flow Rate Enhancement
    • 25+ HP Gains
    • Weight reduction of 11lbs compared to the factory pipes
    • Improved Sound
    • Easy to Install
    • Includes New High-Grade Stainless Bolts & Locking Nuts

    Confirmed Compatibility

    • OEM Muffler
    • Akrapovic Muffler
    • Cargraphic Muffler/Systems
    • Fabspeed Exhaust System
    • Kline Innovation Muffler
    • Soul Performance Valved Muffler
    • JCR Valved Muffler


    Porsche redeveloped the entire exhaust system from the previous 981 GT4 when they developed the new 4.0L powerplant and had to incorporate a modular design for various global emission requirements. This led to a factory over axle pipe that provided massive restriction. 

    F6 OAP 3D Model

    After studying and analyzing this design, Flat 6 Motorsports developed a solution that utilized the factory concept but with enhanced bends and by eliminating restrictive elements of the factory design. We achieved this by utilizing 2.5" tubing with smoothed mandrel bends. Replacing the restrictive factor canister with a smooth flowing staggered Y-pipe design ensures optimum exit flow to the muffler section. Advanced simulation software showed this design to most efficiently distribute exhaust flow. 


    We chose to use proven high-grade materials including T-304 Stainless Steel and an advanced proprietary heat shield that is welded and integrated to the piping. This provides great structural integrity while reducing weight and limiting heat transfer from the piping. The increased flow and reduction in restriction also lowers exhaust gas temperatures (EGT). 


    We include the high-grade stainless steel hardware to make this job a simple DIY for consumers who are comfortable installing exhaust work. This is a direct factory replacement and can be installed in less than 2 hours. 

     Dyno Plots

    2022 Cayman GT4 w/ Stock Headers & Stock Muffler
    Flat 6 Motorsports Over Axle Pipes (OAPs) - Dyno 718 GT4

    2020 Cayman GT4 w/ Stock Headers & Stock Muffler

    Flat 6 Motorsports Over Axle Pipes (OAPs) - Dyno 718 GT4 

    2020 Cayman GT4 w/ Soul Competition Headers & Stock Muffler

    Flat 6 Motorsports Over Axle Pipes (OAPs) & Soul Performance Competition Headers - Dyno 718 GT4