The Helix WRX/STI Turbo Back Exhaust System is a full 3" Stainless Steel Cat Back Exhaust System. Features Mandrel Bent stainless steel Tubing. Followed up by a 120mm Stainless Steel Tip. Also Included in this kit, is the Helix downpipe. The Helix Downpipe is the optimal downpipe for the performance minded Suby owner. This downpipe features a cast bellmouth which provides the absolute maximum exhaust flow and minimum back pressure by allowing the wastegate gases to exit without disrupting normal exhaust flow. The piping is full 3" Stainless Steel (304) polished, and the package includes gaskets & bolts. This downpipe replaces both cats and is designed for USDM fitment only. The combination of the Helix uppipe, downpipe, and exhaust system will yield 30+whp!