[trooperbrett]

It really depends on what motor you have, the stock motor CAN'T go over 4000 RPM or the valves will float, smack the pistons, the crank will come apart and the whole thing will go up in a huge fireball! (just kidding, but it'd be cool, no?) If you have a counterweighted crank, stock or stroked, AND high rev single or double valve springs you can go higher. Single springs are good to 6000, I've heard, but I haven't tested mine. I keep mine (1776 dual port high rev single valve springs, counterweighted stock stroke crank, mild cam, Webers) below 5000 cuz I need it to run everyday. The dual springs are supposed to be good to 8000-10000. So the limiting factors are the valve springs and the crankshaft, also, to a lesser extent, the cam.

So, in a nutshell:
Stock motor below 4000 RPM
Mild Preformance motor 5-6000 RPM
Stroker Street Screamer 8000+ RPM

Good luck, and drive your bug everyday!