Designing a downpipe is usually a simple feat right, no. It's pretty easy to make a make a pipe look like a factory piece. The difficult part is making a pipe with a cat inside to make very close to catless power. Our downpipe was able to extract the optimal amount of flow out of the downpipe with a cat in place. This was done with strategic placement of metal matrix catalytic converter and 3 inch T304 Stainless piping. By playing with the cell count of the cat and the placement we were able to achieve a part that does not trigger a cel and supports high power levels.