Chknhwk....Actually, it does not matter what RPM you are at with the Zex kit, as long as you hit WOT. You can be at 700 rpms and if the next thing you do is mash it, you get juice. I usually try to only hit it in 2nd and 3rd gears. Never in first. As long as the pedal hits the ground, you get N2O....
