I would have to say
1. Good Shocks All-Around (Works, Elkas, Axis, etc)
2. Pipes (T5, Pro Circuit, CPI, etc)
3. Tires All-Around ( Maxxis Razr2 "hands down best")
4. Cool Head w/ domes (Noss, Fast, Prodesign)
5. Skid Plates Full Body( For Safty/Cheap Insurance)
6. 28-33mm carbs (For Extra boost over your buddies)
Last But No Least
PORT WORK, PORT WORK, PORT WORK find a builder and let thme know exactly what your looking for ( Fast Racing, Passion, Herr Jugs, etc)
After all of this is complete you will have a nice and beautiful bike, that is very versatile and will keep a smile on your face.