I can't find a thread on this that still seems to be active, so here goes. I posted my fastest lap at Road Atlanta in my new (2k miles) GT 4. Factory Aero settings. My top speed on the lap was 140, average speed 90.1. Like many others, though, I was hell bent on adjusting the Aero, and did so per the manual. This weekend, I posted a lap within a 10th of a second of the first one, but my top speed was only 131.6 while my average speed was 97.7. In fact, pedal to the metal numerous times the best I could get was 134 on that long back stretch. I also noticed high-speed passing seemed a bit more difficult. Does that seem consistent with your experiences with the supposed drag effect of the Aero? I had already vowed to be more aggressive in the corners, but I assume the Aero adjustment helped me some in that respect. Interestingly, the distance traveled in the more recent lap was .2 miles longer, suggesting that I was faster through the corners, but not as sharp. I realize there are other possible factors at play. I still don't have a clue about tire pressures on my !!$$!!&! Dunlop Sport Maxx Racers, and was fiddling with that all weekend. If I am missing something, please don't hesitate to ridicule me in pointing it out. Thanks for any and all feedback.