Hi guys I'm looking for some advise I took the exhaust manifold from my car to 2 different exhaust places to get there opinion, here is what they said. They did not believe there was enough restriction and that they were very well constructed along the lines of a shorty headers, and they thought I was better off using them along with a true 3" flex section and 3" high flow cats in the original spot in the wheel well and then 3" pipe to the 3' mufflers I have. The other option I presented to them was headers and cut the 3" high flow cats into the turnout pipe which would put the cats into the sills and also the O2 sensor in the sill and then 3" pipe to the 3" mufflers. They thought the flex section was important and the heat generated by the cats in the sill could be a problem. Am I winning or losing very much with either option, the original manifold does have a 3" outlet. Looking forward to your views thanks.