so my car is on the 8800rpm rev limit in 4th gear wayy before the 1320 with my stock IX transmission and 25.3" tall street tires. I'm trying to figure out how much i can gain by just going to a set of 26x9.5x16 Hoosier QTP. its a bummer trying to get 5th gear and spool back up, netting a best of 10.7@133 doing that. a friend was saying that if i go 26" not to get a lower final drive, something about 1st and 2nd are too low and my 60' will suck.. any tips?

 

Math says that it should be 137 given the information you provided.

Those tires should grow at speed, so 140-142 isn't out of the question.

 

shift to 5th will not hurt ET. improving 60ft or 1/8th time FAR MORE important.
your 25.3 tires are likely 24.7. use tire RPM data to calculate, NOT tire size. tires are manufactured smaller to save money. this does not apply to drag and race tires. 26 inch tire will be 26. but they do not grow.