A resonator may help. A true cat, even hi flow cat would help as well. Instead of a rasp you'd get a blargle sound, especially upon deceleration... feels like the car drives itself... back pressure.
I've been considering the dynamax mufflers because in my case, my 14" long fart can sound great when getting on it even though it's still loud with a hi flow cat and a resonator (2" pipes to 2.25" clean final loop), but in regular driving conditions between 3-3.5k rpms it goes blick blick blick blag and it drives me crazy!!!!!!!
Anyway, I had 2.5" pipes with no cat for awhile and it was just a lot of weight and made me use more gas to get that weight around it seemed (no back pressure)...
Don't go smaller diameter for cat cuz it'll just clog your flow.
+1 for turbo