what are pullies

i just read that some guy wanted to change his cam gears.
can some one tell me wot they are and how do they make the car go better.
i thought its better just to get new racing cams

and wot are pullies??

Buying adjustable cam gears allows you to change the timing on the actual camshafts, but you gotta dynotune it or you could seriously fuck up your engine. Pulleys on the other hand are a lot safer except for (arguably) the crank pulley which is the big one on the crankshaft. If it's not balanced correctly it could throw your whole engine off and break shit. Aftermarket pulleys are lighter in weight and take less work from the engine to turn, but are pretty expensive. I paid $200 (with a hookup discount) for just the underdrive, but had a professional put it on correctly and dynotune it.

isnt the big one just called the crank pulley, and underdrive is just the term that they use like "AEM underdrive pulleys" because they are slightly larger and that makes the engine work less to turn the accesories, like how on a bike the smaller the gear you pedal and the larger you are driving, easier it gets, but then your accesories are spinning slower.

Yeah I guess... I changed my post so there's no confusion now.