Another muffler question
 

When I go to buy my mufflers, which measurement do I want to look for? The I.D or O.D measurement for the factory 2 1/4 exhaust. That gets confusing sometimes. Do I want 2 1/4 I.D inlet/outlets or do I want 2 1/4 O.D inlet/outlets?

If your using the stock 2 1/4" flowpipes and tailpipes get 2 1/4" mufflers.

If you choose to replace the flowpipes (between the cats & the muffler) and tailpipes with 2 1/2", get a 2 1/2' muffler.

You may need to replace both flowpipes and tailpipes because sometimes when you try to remove an old, rusted muffler, the connecting pipes are rusted so bad they can't be saved - but not always.
If that happens you're better off with the stock 2 1/4" muffler(s) for now unless you're prepared to replace the entire exhaust system, which you stated earlier that you're not.

FYI: Flow pipes are about $15. each, GT tailpipes can be had for $25. each. Both are available in 2 1/4" or 2 1/2" sizes.