Well if you jump and race this is what I would buy:
1. Lonestar axle, the stock one bends from jumping really easy!
2. Works shock with remote res, the stock bottoms out way to easy
3. Gearing, best use of power.
That should be around $1000
If you trail ride:
1. Trinity Stage IV pipe and header, more power
2. K&N filter with outwears, more power
3. New carb, way more power
4. Adjust gearing to what you need, to make best use of that new found power.
5. If you have enough power without a carb then get skids.
That should be around $1000 too.
I'm a jumper/racer, I would like to buy a new pipe but I really think shocks are my next purchase.