GV Under/Overdrive Units

I don't know how much better it is since I get crappy mileage to start with. It does save fuel though vs. without as the engine RPM drops so less rpm = less fuel for the same mph. so maybe I go from 9 to 12 mpg....anything is an improvement since I run 50-50 race/pump mix.

Did not have to make any modifications to the hump but did have to change the drive shaft length. You will need to check the pinion angle and adjust as necessary.