If he doesn't run it too lean I guess he could add a descent amount of power with a tune because the factory keeps it nice and conservative so people don't blow up their motor going WOT, but squeezing anything over 60 out of a tune without fuelling mods is still questionable. I can't see BMW sandbagging that much unless it wildy changes the emissions characteristics of the motor such that they need to keep it down to pass.

It says HE has a 4.4 with 523 in his sig, btw, not that he claims to get that for everyone with a 4.4.

I know the Dinan S2 (everything, but the supercharger) is expensive, but with the boost in HP & torque comes elimination of any hesitation off the line, as well as a stainless steel exhaust - it all comes down to how long you expect to keep this car - 4.5yrs since I've had the Dinan installed, the car runs great, still original tranny, and at 9yrs old and 113k miles (I bought it used) it still leaps off the line - only have replaced the ait cleaner - I really have to get on a dyno sometime, as well as the drag strip