Hyperflow Exhaust Catted Down PipeNEW DESIGN! The Hyperflow Exhaust Down Pipe with a high flow catalytic converter uses a massive cast 304 Stainless Steel Bellmouth that tapers to 3. 0 inch piping where it connects to the mid pipe. Unlike previous designs, the new downpipe will bolt to any stock or 3 inch aftermarket catback exhaust system. Features: Two piece design: Reduced shipping costs Delete the catalytic converter without having to buy a whole new downpipe (Catless Race Pipe