AVOTurboworld's Gen 3 Cat Back Exhaust System for the 2008-2010 WRX Sedan has a Twin Muffler and Resonated Centre Pipe system which offers improved flow and a deep, smooth sound. The twin mufflers are constructed fully of stainless steel with 63mm (2.5") piping from the y-pipe. The dual mufflers give a great sound out the rear with the AVO 4" round-rolled adjustable exhaust tips. The front section of the cat back is 3" with a resonator, which then runs into a y-section that is twin 2 1/2". 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. The Y-Pipe has an adjustable coupling with a clamp to allow for ease of fitment.