For a full version of the rules, fo here.....
http://www.ndc90racing.co.uk/rules.htm

Basically, the frame has to be an original C90 frame, it can be braced and/or strengthened as required. The frame is the only part that cannot be swapped during the race, so if you break it, it's goodnight.

Engine.

It will be impossible for us to check for internal mods, so basically you can do what you like to it, as long as you use an standard capacity barrel.

have a look through the rules and ask about anything that you need to know.

S1OPP