All

I highly recommend you go take a look on pinkbike.com in the buy/sell section. You will find something.

Did you look on pinkbike.com in the buy/sell section? You should find something there

Obviously you can change any components on your bike but to answer your question the fork, shock, brakes, derailleurs (drivetrain) are the parts most often upgraded as new models come out. For brands, I will say and most people will agree that Fox make the best forks/shocks out there. If your into downhill/freeride, Fox 40's are the way to go...