According to the gearing calculator it'll do 110mph with 14t, 20" wheels at 8K on the motor.
http://www.everything2stroke.com/content/42-Gearing-Calculator-Quadzilla

If you do go that fast on pavement make sure you have good tires and remember that when trying to stop fast on pavement the rear axle will hop like mad.

Plus with that gearing it'll be interesting to see if it can get out of it's own way at slower speeds.

let us know how it goes.