bobber250,
I didn't do any testing of the stock gearing verses the 35 tooth sprocket so don't have an answer for you. I am currently running a 38 tooth rear here in WNC but have run a 33 also. Although I have not run the 35, I think it might be the best size for all around performance.

I'm guessing that the DF and like powered bikes with the CG250 are topped out a true 65-70 MPH. You will need to do a more powerful engine transplant to get 100MPH.

Take all claims of top speed posted on the net with a grain of salt.