Car Bounces after 60 ft. What is causing this??

SpareParts has the right idea, it's called porpoising and is a matter of spring rates. Front and rear spring rates are allowing the weight to rock back and forth. A friends Volare does the same thing but, very mildly. Keep tightening the rear shocks or maybe try a lighter set of T-bars, until it quits. For as quick as the car is you don't seem to get much fronted rise, what bars are in the front?