isnt the pulley the aprt that will help increas eaccleration but will result in lower battery rechariging or something? which emans if you have a big sound system, it wouldnt be wise to do this mods.
because the alternator (the thing that provides electrical power to things like gauges, monitors, and audio equipment while the car is on) is being underdriven (it gets spun by the engine half as much because the pulley is half as big as the stock pulley), the battery will take longer get charged up. this isnt really a problem though becuase you shouldnt really have to worry about it anyway.
it is not smart to use an underdrive pulley on a car with a lot of electrical dependency (lots of subs, amps, monitors, etc.) because the system will not be supplied with enough power from the alternator.
in other words, the stock alternator can power a stock audio system, underdriven or not. it cannot however, power a fully built system, and be underdriven at the same time.
getting them or not is all a matter of what you want, faster acceleration and revving, or a system that you can be proud of.
the never ending descision of show or go...
(and in this case you cant have both