Raven, no one can answer your question based on the information you have given us. It is obvious that you have something specific in mind.
Before you can get a good answer, please provide the following information...
- Exact Make/Model of r/c vehicle
- Exact type of racing surface (include size of longest straight section)
- What tires you are using.
- What body you are using.
Making any r/c vehicle go fast in a straight line is relatively easy. Racing an extremly fast r/c vehicle is a different matter. Unless you are running on a large oval track, extreme speed isn't practicle. While 60+mph looks cool in a straight line, it doesn't look so cool when your car won't turn and you smash the wall at the end of that straight.
The only vehicles that I know that race at extreme speeds are nitro 1/8 on-road cars at very large tracks. Here is a link to a large 1/8 scale on-road track in Ohio (near Cincinnati) - http://tsrcar.com/garage/track/track.htm