This Rebel XD exhaust system is constructed of 4" mandrel-bent 409 stainless steel tubing for maximum flow. Smooth transition bends allow for low turbulence, increasing horsepower, torque and throttle response. This is a "Race Only" product that is to be used solely for competition. Its use is limited to closed-course and open-course racing that is formally sanctioned by a recognized racing organization. Any other use including recreational off-road use could be in violation of local, state and federal laws.