We like Invidia products for their excellent quality and great fit. The company makes several N1 systems for your 2004-07 WRX or STI. Choose from "Race" systems, which are the most aggressive-sounding, with a straight pipe and no resonator. The "Street" N1 is throaty-but-mellow sounding, with the same straight layout as the Race system, but with an added resonator to tone the sound down just a bit. Either is available with stainless steel or titanium tip.

All the systems shown use all-stainless 3" mandrel-bent tubing, with 4" diameter exhaust tips. All have a flat flange on the front, so they'll fit up best to an Invidia downpipe, or other aftermarket downpipe with a flat flange. They CAN be fit to up to the stock downpipe's donut gasket, but it's not going to be an perfect seal.

Fitment note: This exhaust was designed for the bumper cutout of the 2004-2007 WRX and STi. It CAN be installed on the 2002-2003 WRX, but the tip will contact the bumper. You could modify the bumper, or use some to lower the muffler.

Availability note: Supply on Invidia products has been spotty. Please call about product availability before ordering.