But again as I said above
Exhaust bigger than the manifold outlet is pretty much a waste. Whether 2-1/4, 2-1/2, or even a measly 2 inch..... If your manifold is a 1-7/8"bottle neck, pipe larger than that bottleneck, offers very little benefit.
In order for 2-1/4, 2-1/2" exhaust after the manifold outlet to be of any kind of help the manifold outlet MUST be opened up as well!
