I've had all kinds of stuff, Spintech, Flowmaster, Dynomax bullet and even Dynomax super turbos. My current Catback on my Cobra is the Pypes M80 system with resonator tips. Deep, moderately loud out the back but no rasp, no drone inside the car.
Now, personally I really like a little bit of drone inside but that's me.. this sound currently is still with stock tubular manifolds and factory catted h pipe. I currently have a set of Mac long tube headers and VRS X pipe that I'm dying to put on. I imagine the noise level and the rasp will go up but we'll see. I do, however think the resonator tips will help. If you're have no idea what resonator tips are like... Well, they're like a spiral core baffle in a set of motorcycle pipes.. Personally Spintech has my favorite sound but even they may sound different with these tips.
I like the system, I don't doubt that it flows pretty good since it's a straight through system. My one and only gripe is that Pypes is made in China. Having said that, the system is pretty nice and it was on the car when I bought it so it stays.... For now... Atleast. I have other places I'd rather spend my money.