I have it... and it fits perfect! The welding on it is awesome and top notch. It's a direct bolt on and fits like a glove. It comes with the gaskets and is basically 6 bolts. If you have a jack, you can probably do it yourself. If not, take it to a body shop and it should cost no more than $40 since it takes literally 10min if you have a lift. (I paid the guy $30 cash and supervised the install). I would recommend it, but you might get others that have different views. However, DO NOT get the "Kinetix" Y-Pipe... they have a fitment issue where the brackets are touching the underpanel of the driver's side (reason for added noise) causing problems. There's a couple of threads on G35driver.com on this.
My impression of the UT Y-Pipe, more pick up when you open it up. For daily driving, there is almost no audible difference. But the nice growl is nice past 4500rpm.

I don't know about the Dyno charts, but my "butt" dyno tells me there is a lil bit more pick up.