With an auto about 570rwhp could get you about 10.2. That is with a great driver like Mark Cooper though. For a six speed it is probably more reliant on driver than power. For a good driver its probably around ~600rwhp to get into the 10's with a six-speed.
My friend made 436rwhp/475rwtq at BPU+ and then 550rwhp/640rwtq with 100 shot of NOS. Remeber you not only get the NOS but your boost goes up when you hit the NOS. I think he hit something like 22psi when he was on the NOS. BTW he ran 11.29 at 128mph hitting the NOS at the top of second gear.