Garbage in the sense that its mild steel, rusts and falls apart after a couple of years, and is a 2.5" system that turns into a 1 7/8" system at the mufflers. Are there gains to be had replacing the catback alone? Sure, alot of gains? Not as much as everyone seems to think. The real problems with the LS4 exhaust are up front. I am looking into the walker/dynomax super turbo direct fit mufflers for our cars, and ill probably replace that entire catback soon enough as my mufflers are beginning to rust out, found a dime size hole in the drivers side last week and its not long before the intermediate pipe begins to rot through, its completely rusted solid.