We match the exit size to the size exhaust you ordered, so if you are ordering this after the fact, please include the exhaust size you have in your order. Replaces the OEM catalytic converter with a free flowing pipe. Completely straight through (no bottleneck), free flowing mini-muffler and pipe. Replaces the OEM catalytic converter with a 3" metal substrate core high-flow performance cat and our mini muffler. The metal core is our highest flowing cat available and it will&nbsp