The HKS WRX & STi Downpipe is designed as a simple, cheap solution for making power. The HKS WRX downpipe will eliminate both catalytic converters on your 2002-2007 Subaru WRX or 2004-2007 STi, and features 3in piping for optimal flow. While the HKS downpipe will improve performance, we do not reccomend it for anything other than a stock turbo, due to the flat-plate design that does creates wastegate turbulence.
Because the HKS downpipe eliminates both catalytic converters, it is not emissions legal and will trigger an emissions Check Engine Light (CEL) The HKS WRX & STi downpipe does help reduce boost spiking in 2.5L Subaru cars because of the reduced wastegate flow. This downpipe is full 3in with a flat rear flange, so we recommend an aftermarket 3in catback exhaust for proper fitment.
Part Number: 33006-BF001
Fit and finish is perfect. Never had an issue with HKS exhaust components. Don't spend crazy money on a fancy "divorced" downpipe. If someone tries to tell you the "flat flange" Subaru downpipe is a bad design, they have no understanding of how the stock turbo wastegate opens on a Subaru.
Purchase an oem Subaru downpipe gasket. And unless your cat-back is 3", you'll need an adapter.
Rusted bolts and O2 sensor caused a few issues with install otherwise simple to do. Had it 4 months but only just installed. Can hear the turbo whistle and noticeable power increase although not too loud with stock catback. Seems like a quality piece. Haven't driven on it a week yet so can't give long term review. So far pleased for the price. Saved 10 pounds vs stock downpipe.
Welds looked good, paint has not came off with the heat of the exhaust, makes the turbo very audible and sounds very good with an existing cat back system.
No complaints. HKS always makes a good product.
Mates this to the forced performance blue turbo and tomei fatback. No fitments issues, is loud! The welds could be a bit better aesthetically speaking but for the price it gets the job done!