all you need to make it go faster is a 23cc cy head and piston (the xrc has very small ports but very good bottom end)
and maybe a tune pipe
they cars are ok the one in the link is one of the very first ones dont have front brakes and i think the shocks dont have oil in them
the bodys are junk i use a smartech one on my car
have a look here theres photos of my car there
http://www.rcuniverse.com/forum/m_8429061/tm.htm
hope that helps