Quote:

the fuel pump could explain it. sounds like the old fuel pump wasn't keeping up and feeding the beast at high RPM, and the engine was laying down some on the big end of the track, keeping your ET & MPH down. playing with an online calculator,

http://www.dragsource.com/index.php?navselect=calculators&calctoview=4

assuming 3600 lb with driver, an 89mph trap and a 15.31 ET yield the same HP estimation. a 106 trap and a 12.83 yield the same HP estimation.



This is it exactly - the fuel pump. A gear change might add 1 mph. Look at the old 60 ft, and compare it to the new 60 ft, multiply that difference by 1.5, and that is about the net benefit of just the gear/tire change.