Invidia down-pipe is yet another way to improve the efficiency of your exhaust system and gain a boost in power. Each down-pipe features a large 4 inch stainless-steel enhance power by freeing excess gas. Its one-piece design eliminates the need for the stock catalytic converter, reducing restriction and increasing horsepower. In addition, each down-pipe can be bolted up to any Invidia Exhaust or a stock exhaust for an easy bolt-on installation