do i really need 3" exhaust

I have the same set up and TTi step headers. I originally had 2 1/2" exhaust and it rapped at slow speeds and on deceleration. My brother always said I sounded like a Chevy. I went to rolled 3" and added an H pipe. It sounds better and no more rapping. I can't say that I felt any difference in power though. I like my sound a lot better now.