Initially, I intended to put a glasspack I have laying around in place of the muffler. I saw videos and it is really loud but I didnt really care. Now I read that people sometimes replace the cats and resonators with glasspacks, too. Does anyone here have any experience with glasspacks?? From what I read, putting a glasspack in place of the cat does make it sound really nice and deep, but I wonder how much the labor would cost me. And I'm not even 100% sure if '99 Miatas have resonatorss.