Welcome to xc racing! Your machine sounds like its ready to race, don't worry about spending a ton of money on it until you try a few races and see if you like it. If you want a good practice race and your that close to Powerline Park. The AWRCS is racing there on July 27th. Its a great series ,great tracks and very helpful people that will answer any question you have. Your best bet on class at your age on a 400ex would be the sport class -all machines are 400cc or less. If you decide to come out and race the 27th, come find me at the track. I also run an older 400ex, red #484 on it.
AWRCS #484 QXC Senior class - yeah i'm old but i can still ride!
2000 400ex , dg pipe , k&n , ac nerfs and front bumper , burgard +2+1 a-arms, armidillo rear skid , rock beadlocks all around , kenda klaw xc's front and rear , 450r front shocks , GT Thunder front and rear springs and xc link , tusk braided front brake lines and clamps , moose case saver , streamline steering stabilizer , renthal bars , much more to come!