I am currently running some Hooker Aerochamber mufflers. They are header-style mufflers but I didn't really realize that when I got them off of eBay last year, and I had the exhaust shop run them as a regular muffler down toward the end of the system. Tight fit but it works. Anyway, my pipes are 2.25in, and I don't remember if that's what the muffler inlet/outlet is or if they're 2.5 inches. Anyway, I'm going to put 3in headpipes and either leave the tailpipes at 2.25 or go to 2.5in when I install my BBC. Do I have to get bigger mufflers or does the exhaust shop adapt?

bump..

It's up to you if you want to keep them or not. The muffler shop can easily step the pipes down to 2.5" or even 2 1/4" at the mufflers.

If you want less back-pressure and your going through the trouble of installing 3 in. head pipes then if the mufflers are 2.25 inlet and outlet, I would scrap them and put a 3 in. inlet to 2.50 outlet and finish the piping in 2.50.

Thats what I have on my BB chevelle with series 40 flowmasters. Sounds great and moves the exhaust out nicely. Don't forget an H or X pipe!!