Well todays dyno session didn't go to well. Peak HP at 335 was almost identical to the baseline runs and below peak the car was down on power throughout the rpm range. The car is stock except for the cat back. I'm pretty sure it has nothing to do with the exhaust as I've never seen a Z lose low or mid range due to big pipes. After the fact Steve realized he had left the defogger on... which turns the A/C compressor. I'm not sure if that could be it or not. I know the ecm automatically disengages the A/C under either WOT or at a certain RPM but I don't recall the details... anyone remember how that works?