Invidia produces some of the most popular exhaust systems for the WRX / STI. Their designs result in an excellent free-flow exhaust system with optimized back pressure, giving greater horsepower, torque gains and a rich deep sporty sound. The use of SUS304 polished stainless steel piping, mandrel bent to shape, state of the art CNC machine made flange, robot TIG welding and double wall polished stainless steel or titanium tips, provides outstanding durability and appearance.