It was pretty easy to install for me. USDM too.
I've had this kit for almost 2 years and the sound depends on the other mods you have installed. I started with a 2.5" exhaust, crossover pipe, GFB DV+, stock turbo e40 tune, whoosh v1 intercooler, 3" high flo cat. It would sound like it large shop vac sucking in air and when I let off the throttle I would get slight flutter, low exhaust rumbles.
Now I have upgraded piping all around, custom shorter 3" exhaust, GFB DV+, X57RS, 3" On3 performance intercooler, 3" high flo cat. Louder shop vac air sucking sound, louder flutter, and pops when I shift, loud burbles during deceleration.