I know that the DS that won the Baja 2000 did 105. Pipe and jetting. 17-37 gearing. I know. I built it and rode in the race.

 

You could buy top speed, by buying a $15 sprocket, a pipe and air filter, won't give you much top speed, you need a well build motor or changed gearing.

 

with the stock cdi, you might get their a little faster,but unless you racing on a set distanceit wont help much.. the top speed will be the same. 75 MPH IS THE LAW! their is no quad made with stock gearing that will go any faster! dont believe it then check it out.Thats why the ds can handle a the gear change. it had to be geared down to run 75.people talk about their bikes go 81 or 82 stock...BULL! stock bike with after market cdi and air box removed and a carb mounted k&n will give you 2 mph gain.cdi alone with no mods will not give you 1 more mph even on pavement..starting at 73mph top end with a 200 rider. cdi and 37r 8mph gain=81mph.with a k&n carb mount=83mph 17f and 37 rear=89 mph on pavement ..checked with police radar!BELIEVE IT!
ron woods stage 2 with head work and porting and valve work on gas.114mph! running alcohol you can pull even a taller gear. 15f 42r is all you can run with the stock chain for 300' drags.with 4-snows lowered on alcohol and stage 2 with head and valve work will put you in the mid to high 4"s if you get a good hole shot.

 

Mine has stock gear, and tires.The vortex box to lets the motor rev on out thought. It went 84.6 on gps