im not sure about pulleys so i am asking this question.

whats differnts between underdrive and just stock diameter?

and whats better?

 

underdrive is smaller dia. If you have a large stereo you wouldnt want it. If you dont its ever so slightly better due to less rotational mass

 

do they have any aftermarket ones for a 99? all the websites i've seen are only for 00-03

 

go to the just installed ur pulley etc. scroll down and look for the excelerate avatar he has your pulleys i think it's a 99-03 if not he can help you out on getting what you need

 

the 99s use teh same as the 00-03

 

ok i was looking at the difference between the crank pullies on the exhaust question. the picture of the two and something came to mind is the underdrive pulley just for one belt since our cars have two belts and if so how do i go about getting it right. thanks

 

Get Gates brand belts. I'm not sure of the exact size. Do a search for the Unorthodox Racing pulley and you'll find what size you need.

 

both the under drive and standard size are both designed for 2 belts. Contact our vendor excelerate for the UR brand.he will set you up with the correct pulley

 

ok thats cool their is only one underdrive crank pulley for the car the picture on the website it just looked a little different.

 

So I have that underdrive pulley and recently upgraded my stereo w a jl 300 4 channel & a 500.1 pushing a 12w6.. Do I need to put the stock pully back on? is there an aftermarket one made for cars with systems?

 

Yea UR makes a lightweight one that is the stock size.

 

Unorthodox Racing makes an underdrive pulley and a stock size pulley. Unless you have a stereo system over 600 watts RMS or a supercharger you would want the underdrive pulley. The stock size pulley would be for the supercharger or large stereo setup. Both are lightweight, only about 1-1.5 lbs.

 

So is there any performance difference between the two, the underdrive and the stock size pulley that is?

 

very very minimal