Pretty cool mod! My nephew also got a Power Wheels for Christmas. Since his name's Cooper, he had to have a Mini Cooper of course. He isn't quite two yet and can't easily reach the pedals, but he did get the hang of driving it around. It obviously needs to be lowered though, he's got some major wheel gap.

Got the girls a yerf dog 2 seater with indipendant suspension and a roll cage.
Savannah is 9 and can just barely reach the pedals... driving lessens have been "interesting". wide open, or slammed stop. no in between...
It has a 6.5 hp engine...
KC

I bought one of those of Jesse a few years back . . . he kept what little grass grew around the cabin beat down and leaves and pine needles cleared away with it.  It was a pretty neat go-cart . . . it would even pull my big butt around the place.  It was stolen a couple of years ago.