First and foremost: Trash those stock tires and get a set of Michelins on there; 140 X 18 S-12 on rear, M-12 on front. Second, and very critical: set your sag to 95 mm (laden) in the rear. It will sharpen the turning significantly. Third, raise the forks to 10mm above the clamps. Aluminum handguards are a must; save your levers and your hands. Skid plate's a good idea if you ride in rocks at all. Get a gripper seat and save your stock cover for resale; they self-destruct shortly anyway. I don't run rotor guards and have never damaged a rotor. Stock jetting is OK, but vast improvements are possible. Try an OCEMN needle, fifth position, and a 170 main. Get the P-38 modification for the carb, or modify the accelerator pump yourself for a one-second squirt. Consider pipe guard and muffler guard to protect those pretty pipes. I would try to swap your E/XC muffler for an SX muffler, then install a promotobillet end cap spark arrestor--lots more punch and response with this setup. A steering damper is pretty nice to have as well; saved my scraggly butt many a time.
"Again with the squeaky shoes."
'05 Gas Gas 300DE
'02 KTM 400SX/EXC
'02 KTM 400 SX
'75 Yamaha TY175