Dont know where you saw that kind of power listed on their site. This is exactly what is stated by KB. This is there cometition model and of course you will need to get modifications done to switch over to pi heads. Im trying to find the site where non-pi heads are ported and have great flow numbers that you can put the KB made for your ride onto.
On our Dynojet, the 2.6L kit at 20 psi made 682HP on a 8.1 compression ratio 4.6 GT with ported heads, cam and headers. That was 30 more HP than our Cobra test car at the same 20 psi boost. Obviously, the Kenne Bell and Ford 4.6 make for a great combination
Also tranny wise, I had my aode built w/ manual valve body, 2800 street stall(was at full boost at 2200rpms) and line lock. You could put a monkey into the car and run it consistant.