could be wrong, but I dont think there is too much you can do to customise the rad buggy as regarding parts from other buggies, what size is the bolt
in the headstock, if its say a 10mm bolt then obviously anything using a larger bolt is out of the equation, same reagarding other parts of the buggy.
The buggy you have is a starter buggy and ok for learning the basics of buggying, soon if not already you will be amoungst other different buggies and
start seeing that the rad buggy does infact seem quite basic. My advice, rather than wasting money on any upgrades, sell yours onto anther new buggier
and move onto something better.