Eh... It sounds pretty flat and unremarkable right now. I need to add a resonator and I've been chasing exhaust leaks for months now. I thought it was the slip fits at the header collector and the muffler inlets, so I tried sealing them up with a several of increasingly nasty and permanent goos, but I the last time I pulled them off I realized that the v-bands were leaking. The ones I used were cheap, and are a little warped after welding, but since they have a locator ring in one side, you can't just plane them flat. I'm going to replace the header flange gasket with a new OEM one and sand the locator ring off the male side flange the next time I can get the car in the air, but I just haven't had time lately to mess with it.
As for the diffuser, I do my own carbon fiber bits for side money (when I can find the time between school and working on cars to make ends meet), so I'm going to do my own chin spoiler, splitter, flat belly pans, side skirts and diffuser. Hypothetically. Maybe.