HKS Silent Hi-Power exhaust Brand HKS (Japan) Website HKS-Power.co.jp Part number 31019-AT009 HKS replaced their Hi-Power cat-back exhaust system with the Silent Hi-Power system. The new model should be a bit more quiet but the main advantage is that it's completely made out of SUS304 stainless steel whereas the Hi-Power had mild steel piping. The Silent Hi- Power is a 3" system and approved by the Japan Automotive Muffler Association (JASMA). The HKS exhaust comes with gaskets and mounting hardware, a manual and a sticker Angle! Related links How to replace the exhaust Modifications - Engine Top