The check will be in your name. We all know someone who has kept the check and didn't fix the car. As for the exhaust, typically it is the design of the muffler that increases sound. The less chambers it has and more straight through the design, the louder. That said, A bigger pipe will be a bit louder and those big tips (echo tips)act as a megaphone. Too big on the pipes and tips sounds bad anyway. Stick with a nice muffler.
97 Cobra w/T56, alum DS, SPEC111 clutch, 4:10's, T&J Performance Forged 4v(8.9:1), Manley H-beams, Novi 2000 (21psi w/ 2.7'' pulley) Fast Track A/A I/C, Accufab 1696cfm TB, modified intake, Blow-through meter, Barry Grant Fuel syst., longtubes and H-pipe, 40 Flows, MSD ignition, Detroit True Track, 315 NT01's on 17 x 11's, 640 RWHP.