408 stroker exhaust question

I have a 408 stroker and am running 2 1/2 inch all the way out the back and some tiny little Flowmasters. The popping out the back at certain rpm's is annoying, but when I get on it I love the sound. I am thinking of going to 3" to lose the popping noise. I think going to 2 1/4 will choke out a lot of the inherent power of a 408. Can you modify the stacks to 2 1/2 or 3"? That would be ideal, because that is the look you want, and IMHO they need to be operational. It's just cool.