Your engine work most efficiently at a certain A/F ratio. If you have more (too much) air - then your lean and detonate. If your rich (too much fuel) you do not have full combustion and you loose HP; which = mph. We did just this last weekend at Atco. We ran our second run at only 124 mph; our A/F which is usually 11.5-7:1 was a rich 10.2-4:1 We lost over 6 mph.
Hope this helps you.
Dont mean to buttt in.. but your chip controls injector duty cycle. So if you run a 60 lb injector at 50% duty cycle is the same as if you ran a 50 lb injector at 60% duty cycle which is the same as a 40 lb injector at 75% duty cycle..
See it all adds up to 30 lbs of fuel per hour. Running smaller injectors is foolish on a motor that one is trying to extract HP from. And running injectors at STATIC is foolish.
My engine runs 75's at 60% duty cycle. I could technically run 50's at 80%.. but like the added margin.
So adjust your injector Duty Cycle to obtain the proper air fuel target numbers your trying to obtain.
HTH