I just upgraded my 22RE exhaust with 2-1/4" pipes, mandrel bends, cat and muffler. I went with 2-1/4" from just in front of the cat all the way back. Only my primary (head) pipe is 2". It runs noticeably better than it did with the 1-3/4" NAPA muffler and tailpipe and the sound is only slightly louder.

'89 4runner SR5, 3.0, auto (fun)
'93 xtra cab, dlx,3.0, 5spd (work truck)