Got great gains, but it's pretty gnarly down low (raspy like crap) but up top it sounds pretty good.
I have Magnapacks, so the combination of the two equals a really loud car. I haven't really had any formal complaints just yet, but often get comments about it either sounding good or "I could hear you coming".
It's fun during the day, but can be slightly embarassing if you're pulling into your neighborhood late at night.
I like mine, I'm still using the stock cat back though. I noticed some gains over 3500 rpm or so, its a good upgrade. Quality was good, installation a snap, $150 shipped.
Yeah, you'll need MILS, I got mine through UPR and haven't had a problem in the year that I've had the pipe. Love the sound and it makes the car feel a whole lot better. It fit good and has great quality for the price. A+
I have the UPR with flows. Lost a little power down low. Car sounds unreal now. The idle sounds mean as hell. Once the car is warmed up, when you switch gears or drop it out of gear and let the RPMs drop from 4000 or so down to 2000 or lower the car sounds utterly amazing. EVERYONE compliments me on its sound, and it always turns heads. Everyone drops the "I could hear you a mile away" or "Your car sounds awesome!" Car sounds MUCH meaner/faster than it really is
Complaints: It's loud. Loud as hell. Sucks on long trips. The 2500 RPM drone is DEAFENING.