Ey Up Truckers,
Lower the front as michael says above, glue some lead in the open space behind the guide, glue the motor in, and fit a 30t Slotit gear.
You can go further by fitting NSR wheels and tyres, but its not essential, and can give too much grip, better to slide a bit.
One other thing, the mirrors are vulnerable, so make up small wire guards and glue into two holes drilled in the body.
vbr Chris A. ( wood track, no magnets !! ).