"The best setup cost wise we have found is to use the excellent factory exhaust manifold, then increase the pipe size to 2" all the way to the muffler, yep, the cat, too. Then we increase again to 2 1/4" on exit all the way back."

My muffler is ready for replacement so I'm going to upgrade my exhaust system according to Ted's recommendations. The system is stock size, and my cat seems to be in good shape.

Will I still benefit from increasing the pipe size to 2" starting at the exhaust manifold, even with the stock sized cat pipe input and output fittings?