The GMMG is the best catback available for the F-bodies (The Borla I had was amazing too, but just as expensive as the GMMG). Amazing sounding, but a lot of guys will argue a true-dual setup sounds better (Usually have to dump them under the car though, and must be custom made).
The LT1s usually are said to sound better as well, apparently it has something to do with the iron block vs the LSx’s Aluminum block? :/: They both sound good to me (but different). Any of the LT1/LSx engines + Cam + Catback + Headers = Pure sex. I’m still trying to plan out when I can possibly buy one of these machines again at some point. They’re addictive.
Search youtube for “TFBM” for some good auto-x videos.