Got my first try with 4s (first 4s) on my new buggy (and first 1/8th ever). Sportwerks Mayhem Pro, Mamba max, 7xl, Maxamps 4s 5000HV. Holy cr*p, this thing flies! It is very silent too, alot queiter than my MT2 18SS conversion. At part throttle, you can hear the driveshafts clicking, but no gears or motor noise. At full throttle, it just makes a powerful whine! Whoo-hoo, this should really smoke some nitro but. The shear acceleration of this heavy (still less than 8lbs) buggy is amazing!