I installed mine tonight...did it without a lift, and just a pair of jackstands and a jack
I think I spent about 3 hours on it...most of that trying to bust loose the OEM exhaust. I didn't jack the car up very high, so I couldn't use a breaker-bar or really anything...lol. A couple times a bolt would come off one side, only for the other to be tight enough to have a molecular bond.
After all hat work, of course I took it for a spin w/ the wife since she helped me (fetching tools, complaining, talking too much, and handing me parts, you know, the usual stuff...) - butt dyno says a good chunk of gainage!...volume inside is quite a bit louder, and there is a definite (to me) drone at the 2K region with a 7AT (but the radiop does overpower it and you can hold a conversation over it without having to speak up...) - which equates out to be around 60-65. 70 and up it's less noticable. It's really noticable if you use moderate-light accelleration to where it doesn't downshift, and it just RUMBLES that much harder. Bumping the accel button the cruise is a good example...in fact, it rumbles hard enough to vibrate the steering wheel!
Overall I think I like it. The loudness in the 2K region might bother me, but I think some sound dampening material would help with that.
Definately sound more "racey" now - I just kept hearing Forza 3...lol
One othe thing, I think I'll take my car to the dealer and have them put it on a lift, so I can really torque down those bolts. I got them pretty snug, but they aren't NEARLY as tight as they were from Nissan...