You can't just swap out a nimh pack for a lipo and use the same setup without having some problems, same as you can't yank the silver can and put in a stock motor without seeing major changes in the way your car handles.

But if you take the time to change your setup and tires- which takes a LOT of time and experimentation- a non-weighted lipo car actually runs quite well and doesn't roll over any more than a nimh car.

Nonbelievers should check out the Tamiya track at Aliso in two weeks...