When I bought my car it had glasspacks on it. It sounded pretty good until one cold day I noticed that exhaust was only coming out of one side. It looked like I had fake ricer dual exhaust When I removed the glasspacks, the pipe on one side was completely clogged with fiberglass bull****. Two weeks later a package arrived with a MAC o/r h-pipe and a MAC cat-back. The sound is 100 times better, and now I don't have to worry about the fiberglass clogging it and reducing my already pathetic HP numbers.