I built the exhaust system for Johns truck today. Stock was 2" to the cat and then 2.25" after that. I decided to step the whole thing up to 2.50" tube with all mandrel bends, a high flow Magnaflow cat, and a Dynomax Thrush welded muffler, which is similar to a Flowmaster design. It is all TIG welded aside from the hangers and where it meets the 2" - 2.50" reducer right at the manifold.
