I was at the track last night and I figured I'd throw it into OD at around the 1000' mark just to see how'd change my time. (Yes, I had to go to half throttle.) Well, I gained a tenth and lost 4 mph.

Could this mean that my engine is out of breathing room in 3rd gear by that point and is not pulling as hard as it could? It's basically a stock TPI with headers and catback. Stock 3.27 gears.

 

between having to go to part throttle and the engien being able to breath easily at the higher rpom in third gear you will lose a lot by going to 4th.
later
tim