These BBK Performance Camaro After Cat X pipes are designed and built to out flow the restrictive factory resonator setup The High Flow X pipes are made with 2-3/4" inch CNC mandrel bent stainless tubing for maximum flow over the stock pipe and they are specifically designed to increase performance and horsepower. As an after-cat product they are smog legal as they do not interfere with any emissions controlled parts. These exhaust pipes offer increased horsepower and torque over stock and sound great on all the Gen 5 Camaro applications.