Mark, it was a full replacement to OEM, I used the same hardware as the OE hood. As far as fit,it's not perfect but no aftermarket hood will be. This hood is a siebon which is one of the better CF company's. I'm satisfied with the fit and finish. Also, if you don't like the look of hood pins don't get a carbon hood, lots of people run without them but at 75mph I see mine shake and that is most likely due to the scoop but I've seen more than few fail and slam against the windshield at speed. Just to be clear, if you go carbon get hood pins, I recommend Aerocatch, you can see how they look in the outdoor shots, I tried some NRG's but didn't like them, they are the ones in the garage shots.
Chris, the 06-07 Impreza's come stock with an aluminum hood so there is no weight loss. A carbon hood will not help with heatsoak, Iwould say a turbo blanket will help but I say do some research on NASIOC.com.