Allan any pictures? The price of replacement mufflers and CATs, unless you go OEM is off the charts. If you are not drawing any stares you are doing good. I would like to do a similar system maybe using Borla mufflers and Magne Flow CATS instead. A good spring project or until I can no longer put up with a rattle that just begin to show up when I stop at a light.
I've seen a Flo master on a 535i. Very odd looking, as it was actually mounted on it's side and the exhaust tips were twisted about to end up side by side instead of on top of each other.
Local guy has a custom 3" set up for his turbo '89 525 that I believe uses a cat, no resonators, and a muffler. I'll double check.
Sean H
'02 325ci
'84 318i GTR