For exhaust I have n55 mid pipe on a n54 and berk race axel back; so it can get loud. I don't think my setup is too loud, however it depends on how I drive. I can drive the car in a way that is quiet. Drone seems to occur around 2k rpm, 2.5k rpm, 3k+ rpm. Cruising at 75mph my car is fairly quiet, however cruising at 80mph it drones.
Reminds me of my rsx-s with injen cai, race header and apexi n1 catback. Thing had no cats and it spit fire WOT at any shift past 7krpm, and was loud as shit but 80mph(4k rpm or so) cruising on the freeway it was so quiet I could barely hear the engine.
I guess my point is that the maddad setup is pretty quiet compared to what I have and at most cruise rpms it will sound like stock. So don't worry about added noise just doo etttt.