GrimmSpeed Catted Downpipe 2008-2021 STI / 2008-2014 WRX

GrimmSpeed knows how important efficient exhaust flow is and designed their catted downpipe to improve just that. GrimmSpeed uses 3D scans of multiple OEM downpipes to account for any variances within stock parts, and perfect the fitment on theirs. The tig welded downpipe starts with CNC’d mandrel bent 16ga 304L stainless steel tubing and 1/2 “ flanges to ensure durability. The divorced wastegate was located with CFD simulations to confirm optimal flow is achieved. It is then reintroduced to the exhaust flow before flowing through the custom sized 300 cell cat.