Exhaust System on '67 barracuda
You can run 2.25" tailpipes out the back, no problem. Just carefully route it around the fuel tank strap J-bolt on the right side. I slipped a piece of rubber hose over the bolt so it doesn't rattle. I am using a pair of Walker Super Turbo mufflers sized for a 1968 Barracuda 340.
I'm guessing 2.5" would work, too -- you would just have to be even more precise.
A 3" single on the left side to the Commando resonator would be plenty of flow, too. And it would sound better than Flowmasters.