I agree. Hitting 50mph on 2s provides a 100% gaurantee to not hit 75mph on 3s. Increasing voltage by 50% would only increase speed by 50% in an ideal world.

Yup, wind resistance, more weight, ect. are all factors that would have to be figured in.

i assume you mean me sinc e i dont see anyone with that screen name.
i have gps'd mine with a garmin etrax (the yellow one) and reached 50mph with the 2s (7.4v) and did it in less than 200 feet. i dont know the exact distance, but one day i am gona chalk off the road and see, or i might wait until the parking lot is paved for the new walmart below my house and go down there and run.

yeah, OP = Original Poster. Thats cool that you hit 50mph on only 7.4v. I've been runing 8.4v (7 GP3300) on an 8s motor and could only hit 41mph (same GPS unit you have) but I'm seroiusly limited by area and radio interference. I've got about 100ft of straight road in my apartment complex but my radio range is only 50-60ft. I need to stop being lazy and switch the cheap traxxas tx and rx out and install a JR setup I have stored somewhere.

Actually, 65 mph is possible w/ 3s lipo. Here are some 60+ mph rustlers:

http://www.swami-rc.com/speedrecord.htm

As you can see one, of the rustlers did 66.6 mph only on 10 cells with the lehner basic 5300.

well quite honestly, i should be able to easily throw down 60mph when compared to a rustler. my truck is highly modified and just for street racing. its still a work in progress, but i refuse to believe that i couldnt smoke any rustler out there, of course i would prolly have to upgrade motor/esc to match, but there are very few trucks out there that are as mechanically moddified as mine.
so i will let the gps speak for me.
again, any word on the mamba max?

True, but I was referring to his original goal of at least 75 mph. ;)

i went ahead and ordered the cc7700. i cant wait until it gets here and i can run it.