I had no real drivability problems with the Autothority Stage 2 chips, as in surges, etc. I did have a lot of turbo lag, though, and the car never liked to pull at low rpm/par throttle. For example, I never used 5th below 2500 rpm (65 mph) on the flats, or 70 mph if there were gentle hills. With the new GURU chips, there is way less turbo lag, and the car just feels stronger at low rpm. 5th pulls willingly at part throttle down to 2200 rpm; it makes the gear much more usable in traffic.

Regarding HP gains per psi boost, the stock 951 only has 7.5 psi boost at its 5800 rpm HP peak. Compared to an early US 944, (217-143)/7.5 = 10 HP/psi. The Turbo S has the same peak boost as the 951 (11 psi) but holds 11 psi to 5,800 rpm. It gains 30 HP, so the gain per psi is (247-217)/(11-7.5) = 8.5 HP/psi. Remember that these are shaft HP, so subtract 15% when comparing gains for rwhp.

 

Yeah, I did that, but thanks!

I'll probably end up with Guru too, this peer pressure is too much for me.