Brushless E-maxx vs. brushless Aftershock?

[Klausen]

I am having these 2 cars in my garage, and I have one issue.

The E-maxx is hopped up on nearly any part of the truck, and is running af HV6,5 and 2 x 7,4 maxamps 6000 mah. lipo.

The Aftershock have the Finedesign conversion with an XLT1 motor and Castle Hydra 120 esc.

The Aftershock launches reaaly powerfull and have a high topspeed, but is quite easy to keep on all 4 wheels.

The E-maxx also lauches real powerfull, but wheely at half throttle or so. I have tried to loosen the slipper, but then it just spins around, and launches quite slow.

Do you guys know what could be the problem, cause it is rather anoying riding on 2 wheels all the time. I guess another slipper could help, but another thing I have thought about is the tires. I am runnning stock on the Aftershock, but on the E-maxx I run Proline 40 series mashers. Could that be it?

You can see the trucks here:

http://www.rcgalleri.dk/html/gal_vis...2166&ipc=18843

http://www.rcgalleri.dk/html/gal_vis...9719&ipc=71502