The worlds first bolt-on 3.5" Stainless Steel (304) turbo to tip race exhaust designed for 600+ horsepower. Minimal exhaust back pressure, fast turbocharger spool-up and maximum horsepower is guaranteed. The APS DR Series 3.5" Turbo to Tip Race Exhaust is a true 3.5" internal diameter exhaust system through each and every section. By utilizing the latest technology precision mandrel bends with the smallest possible bend angles spread over the maximum possible length, optimum exhaust gas flow minimum exhaust back pressure is achieved.