just a reae end gear math question ???
 

if i had a 3.90 gear with 36 tall tires and went out the back door on a 1/4 mile at 144 mph and 6100rpm what would 4.57 gears on a 1/4 mile be ???

Depending on if you shifted at the same point I would guess around 7000. Go to www.wallaceracing.com and he has all types of calculators for changing stuff.