Originally Posted by ResJudicata
I gave much deserved rep for being the guinnea pig.
I have a question for focusboy, or anyone else. If I wanted high flow exhaust (this header and full 2.5" exhaust) what are some muffler brands/models to look at to keep the car fairly quiet. In a perfect world I'd like to have a full free flowing exhaust that is just as quiet as stock.
Also, has anyone tried (or have links to flow tests) of some of the high flow cat's sold by companies like Magnaflow? I'm curious if it is possible to have a aftermarket cat that still flows fairly well that would stay legal for some who need it. Of, if the whole high flow cat thing is just marketing crap.
The cat no matter what size you use is a big restriction on the flow, however it should be more than enough to pass inspection everywhere except cali. From the research I have done on cars that have an easy to remove stock cat(350z), they seem to add up to about 3% over stock cat, the same cars with no cat were getting 10% so you could probably lose 70% of the gains from the header going high flow, vs catless. But until somebody tries both on a syno it will be impossible to know for sure.