remove stock mufflers and add resonators only?
 

Has anyone removed stock mufflers and added resonators or glasspacks only? How does it sound? Any issues?

Why would you do that? For about the same money you can get a 2.5" catback system with turbo mufflers from Summit.

It's not that loud, more tame, I would opt for a cat back.

Hmmm, my 05' has no mufflers on an otherwise stock exhaust. It flows pretty well and sounds raunchy. May be a little loud to some but to me for a mustang it frickin sounds cool! I bought my car used and it had Flowmasters on it with rusted out baffles so I had a friend yank um off and welded the tips back on. Cheap alternatives to Pypes Pypebombs!

If you're going this route, I would put straight pipe in place of the stock mufflers with the factory H, and cats. When you get a new mid pipe, then add a cat back. I think straights sound really good, just youtube some videos.