Huge 4 - inch constant - diameter mandrel - bent stainless steel pipe outflows stock by 26 Percent. Straight - through muffler virtually eliminates backpressure. Retains factory catalytic converter. Includes Turbine Outlet Pipe and 5 - inch Chrome polished tip. Stainless, 4 - inch constant - diameter pipes and straight - through muffler outflow stock. Virtually eliminates backpressure and lowers exhaust gas temps. Throaty sound. 5 - inch polished tip. 100 percent stainless system extends engine longevity by maintaining the turbine outlet EGT safely within the stock recommendation. The 3 - inch Turbine Outlet Pipe, which replaces the smashed stock piece (see below), flows 728 CFM at 1 PSI, beating stock by 26 percent and the nearest competitor by 12 percent. The streamlined 4 - inch exhaust pipe and tailpipe are formed of heavy - wall tubing with constant - diameter bends to slash backpressure.