speed limitation

ok i have a 96 jetta glx vr6 all stock what are some things to start off with to give it some extra power. whats a good website to look for performance parts.

In advance - thanks for your help! My daughter just bought a 2000 Jetta in Chicago and drove it to upstate NY for her summer job. She made it as far as PA before the "check engine" light came on (this is after having the car completely checked out prior to purchase, spending $1600+ on a...