100% T-304 Stainless Steel Construction Compact Size Fits All Racing Applications Ultra Lightweight-Less Than 1/2 lb. each Little or No Power Loss Easy Bolt Installation Insert Cones on 3", 3 1/2", 4", 4 1/2", 5" Turn Down with Insert Cone in 3", 3 1/2", 4" How It Works: The Vortex Insert Cone, installed near the exit of the header collector or muffler outlet, provides a large friction area to reflect and dissipate sound energy, thus reducing the dB level. The open area of the cone is actually greater than the area of the collector or exhaust pipe, thus reducing a backpressure condition. Because no significant backpressure has been introduced, the engine is still able to use the scavenge ability of a good header to creat horsepower and torque. Dyno and track testing show significant noise reduction with little or no power loss.Pit Stop USA offers Dynatech Vortex Cone Insert Muffler - Slips Into 4" Collectors 772-32530 at low everyday prices. Be sure to check out all of our products from Dynatech including Dynatech Vortex Cone Insert Mufflers.