997/991 GT3/RS – Active Side Muffler Bypass Pipe


More Sound. Less Weight. No Drone.

TPC Racing Active Side Muffler Bypass pipe provides Cup car sound and weight reduction of 36 lbs. The active valves work in concert with the car’s existing sound control system to provide both powerful Cup car sound and street civility with no cabin drone. The weight reduction improves handling and acceleration performance. The rear tire pressure/grip becomes more stable without the radiating heat generated by the bulky and heavy OEM side mufflers. The external temperature is reduced around the valve cover and the ignition coil areas.

How it works

Using a factory-style actuator-controlled valve, the TPC Racing Active Side Muffler Bypass System provides Cup car sound and exhaust flow performance in higher rpm/higher load ranges, while eliminating unwanted cabin drone and excessive noise. Its lightweight design saves 36 lbs from the OEM side mufflers. This weight saving is more than just static weight since the bulk of the stock side muffler weight is located at the far end of the car causing “pendulum weight effect” during cornering. The dynamic weight saving is massive resulting in improved handling. Better exhaust flow management (more direct flow path) allows for a slight increase in torque between 2,600 and 5,600 rpm.

The factory GT3 Cup race cars have similar exhaust design (minus the sound control valves) for the aforementioned performance benefits. TPC Racing Side Muffler Bypass Pipes are designed, tested, and manufactured by our in-house sports car fanatics for use by other fellow sports car fanatics.


  • 36 lb of Static Weight Reduction (Huge Dynamic Weight Reduction)
  • Factory-Style Actuator-Controlled valve
  • Carefully designed upper pipe merge section and bend radius to optimize sound level for long distance cruising comfort and for not drawing attention when attention is unwanted
  • Significant time and effort spent making each conical collector to allow the entire main pipe to be consistent diameter (no step-down size) same as factory Cup car
  • Metal Flex Joint for Easy Installation and Reduces Chance of Center Muffler Fatigue
  • Metal Flex Joint is Protected by Stainless Steel Braided Covering
  • Beautifully and Robustly TIG welded by Master Welding Technician on our precise Jig Fixture
  • Each Unit is Handmade in the USA at TPC Racing, 100% Smooth inside the pipes and in merge areas, consistent inside diameter throughout the entire pipe
  • Stainless steel material is X-ray tested and exclusively from Woolf Aircraft Company made in the USA
  • Sound criteria designed for use with OEM center muffler or 991 Cup center muffler


Experience cup car sound and performance for your 997 or 991 GT3/RS, while eliminating unwanted cabin drone!



Additional information

Weight30 lbs
Dimensions18 × 15 × 12 in