It's pretty much a slam-dunk to put on, although I'd recommend a lift. A friend of mine has one. You will need some shorter bolts and springs for the flange behind the cat, the kit does not come with them but the stockers are too long. The Gibson has fatter pipe at 2.5". It is a little tight where it goes over the rear axle and you have to fiddle with it some so it doesn't hit the pumpkin. Do a search, I posted a more involved thread about it.
The OE system was only three months old and covered in rust. I roughed up the Gibson with some sandpaper and painted it with silver hi-temp paint. No rust yet.
It IS loud, especially when the engine is under load. Especially inside. You may need to tighten the clamps up once or twice afterward if you put it on with hand tools.
I was going to make a separate post about the mpg on my recent trip, but the break-in switch recently went off at 10k miles (this is my third 4.0 SOHC, they all do that), mpg took a jump, and on a level Interstate in Florida with the cruise set on 70 we were knocking down 22 mpg. Mileage in town, not much improvement.
