Well, Under the categories ENGINE, SUSPENSION, and DRIVE.
Engine: Starting with pipe, I would recommend a better brand than FMF, like a Factory 7, Toomey, Bills, Shearer, just anything other than FMF. Another thing that might be good on your engine is some nice Carbon reeds, the most known brands are Boyesen and VForce, both make great reeds. Let me sugest one more thing, that is, Intake. Including Air Filter and Carburetor. You need to be running the proper jets in your Carburetor because you could not be benefiting from the performance upgrades. Infact, you could even blow your motor and have to spend around $250 to fix it in most areas. Air Filters are important because they let your Motor breathe better. You will have nothing if you re-jet and get a pipe without letting your atv breathe. Uni makes a good product and so does Twin Air and K&N. Thats about the basics.
Suspension/Handling: There isn't much to talk about in here but basically, if your going to be jumping tabletops, singles, doubles, and even triples, you for sure are gonna blow your stock shocks out and even get really hurt. Get some nice Racing Shocks. Fox Shox, Elka, Works, and Ohlins make great shocks (More brands to list, just too many). Another that is good to have a nice spaced out quad. On my blaster i have 2.5in rear wheels spacers on each side for a total of 5in wider quad. This helped me alot when i take tight corners and stuff. Along with a good spaced out quad is good tires too. I have 18in ITP Holeshots (MXR6's to be exact) that work good. ITP's and Maxxis are both great brands.
Drive:This is a description that is kinda medium sized. Drive is important if you want more torque/acceleration and Power/speed. If you increase front sprocket teeth, you get more speed. If you decrease the front sprocket teeth, you get more torque. If you increase rear sprocket teeth, you get more torque. If you decrease rear sprocket teeth, you get more speed. If you end up buying new chain and sprockets, make sure you get an O-Ring chain since your racing. If your swing-arm is stock it would be good if you got an extended swing-arm because it helps with jumps so you dont land it on your 2 rear tires. I hope this enough to tell you about your drive.
I hope this helps you get started with some stuff to get to race.I:I