Ran 4s for the first time!
I have an Ultimate 4x4 with the following upgrades. MMP 2400kv, Al. Motor mount, MIPs in front (waiting on rears). I used two identical 5800mah 2s's in series. Wow it's really powerful! Right now I'm running a 20/50 gear ratio and plan to slowly go up. It's a pretty crappy day out today so I didn't bother to strap on the GPS. In fact i think I need to find a more suitable place than my street for speed runs.
It's so powerful that I have to go easy with the throttle. I want to do some testing but at an estimated 20 to 25 mph, if I hammer the throttle it hangs a somewhat controllable wheelie. this is without a body on and the associated aerodynamic lift.