I am getting my exhaust completely redone. With brand new
2 1/2 inch pipe from the exhaust manifold all the way back. My 80's Series Flowmasters will be here this week. Is there anything I could do to make it sound better or flow better? Adding the new pipe should make it better since my stock pipe got rusty and corroded. I am also putting on some mega tips that are 2 1/2 in and 4 inches out, so that would help to.

 

If you want better sound and flow, I don't think you can do much better than what you have planned, short of headers and 3" intermediate pipe. With your planned setup the manifolds and then the 2-1/2" I-pipe will be the bottlenecks.

 

The 350 will be choking on 2 1/2 in. pipes unless you are running duals. A 3 in. is what that thing likes best, it has been proven over and over.