ok first off f22b1 blew a hole in my muffler i dunno how but bought a dynomax muffler ok is the stock exhuast piping 2 1/4??? the muffler i ordered is 2.5 because i wanted a deeper non ricey sound but i have to get a high flow cat not a test pipe "so annoyin" gonna get a dynomax prob but do i need the inlet 2"1/4 and outlet 2.5 what kind of gains should i expect im not thinkin anything over 10 right

 

You're not going to get **** realistically. Please just search.

F22's do not respond as well to I/H/E as some other motors and you are certainly not going to gain 10hp from replacing a muffler with some random brand one while keeping stock piping. And a high flow cat at the same size as stock is just silly.