Check with your local track about engine size. Most tracks let you race what you have. I race my Evader at 2 local tracks and they don't care in the novice / intemediate level. One of the tracks says your must be R.O.A.R. legal for the "expert" class. Go watch before actually trying to race. See what the other racers are using for tires, suspension settings, etc. Look over the track for tough spots and where other racers crash. Talk to as many racers as you can. Try to go practice on the actual track before racing, if possible.

As for the Evader, the things I consider "must haves" are:
1. Metal gear high torque steering servo with a new aluminum servo arm
2. Higher weight shock fluid (50wt - 80wt, depending on track)
3. Inline fuel filter
4. Spares
- Glow plugs
- Batteries (if not using rechargeables)
- Ball cups
- Tie wraps
- Spur gear
5. Adequate tools to do track side repairs and adjustments

Make sure your gear mesh is okay (between spur gear and clutch bell pinion)
Make sure your slipper is adjusted to track conditions so that yo're not fishtailing all over the track on starts and coming out of curves
Make sure your differential is adjusted correctly
Check all screws and nuts for tightness
Make your goal in the beginning to run as smoothly as possible and not crash. Don't fight for the lead right off the bat.

Good Luck.