I have a '99 380 EXC, which I am preparing for sale, that has been a great bike. Here are some things to look out for:
The 50mm's were fantastic forks, but watch out for the seals. I would suggest getting some fork skinz for em.
Some people believe running your chain too tight loosens the sprocket bolts, prematurely wears the chain and sprockets, beats up on the transmission and wheel bearings and makes your suspension bind up. Heres the procedure to set the tension that I plagiarized from another site:
-Take off your rear shock and move your rear wheel through it's stroke to determine the chain's tightest point. Make adjustments at that point. Replace the shock and make a note of chain tension (like 3 fingers at chain guide). From there adjust with at least 1/2" of play. Find a good method to mark this for the next adjustment. A good reference is when the bike is on a stand with the wheels hanging freely, pushing up on the lower chain, midway between the chain slider and the chain guide, will just barely get the chain to touch the bottom of the aluminum swing-arm.
Hope this helps.