AVOTurboworld's Gen 3 Cat Back Exhaust System for the WRX EJ20 2001-2005 is constructed from 3" stainless steel, and designed to bolt up to the stock location flanges. The high-flow design is rated at around 89 dB, making it a good choice for noise concious performance-oriented customers. Comes with a 4" round-rolled adjustable exhaust tip.
The AVO cat back has a tapered flange at the front so that it can fit a standard OEM front pipe with a donut gasket setup. This will ensure the flex in the system still operates as it was intended to from factory.