I added a 1320 exhaust system when I installed my supercharger. I thought it was loud at first, but got used to it because I wanted to drive. It is too loud, so now I am making my own exhaust. I know that my system may end up being loud, but it will be different.
I am using a Borla muffler, and resonator, along with a high flow cat. I really only added the cat in hopes it will also act as a muffler. So, it will be 2.5 inches throughout, but it starts with a 3 inch flex coupler and the cat is actually 4 inches. The cat is rated for engines up to 500hp. I am also making this side exit. It is really tight in the engine compartment, and I started by cutting down the inlets and outlets of the muffler and resonator to shorten everything.
Along with this, I bought a tig welder and am going to do this myself. I talked to a professional welder, who will step in if I need help.