i'm just sharing as wat i know...might mis out few things..
every car have a cam pulley which located just beside your engine and which carry out wit timing belt...usually cover by a cam pulley cover..if u look at it, it is like some sort of gear,tat in a big size...search google to look for how it exactly looks like
adjustable cam pulley is a cam pulley which the location of the cam pulley is same as original BUT is adjustable..u can either adjust it into advance or retard..depends on which one u would like to play wit..
advance is for low-end while retard is for high-end..
once u choose advance,u wil lose power on high-end..however once u choose retard,u wil lose power on low-end...is vice versa..
u wan play pickup,go for low-end (advance)...u wan play street race like while driving on the highway starting 3rd gear onwards,go for high-end(retard)
u wil notice a bar like ruler on the adjustable cam pulley...the origin position usually at the mid...so for retard,adjust it to left side and for advance,adjust it to right side..
tat's for wat i know... :)
beside,i think they are few thread posted regarding on adjustable cam pulley..u can try search back if u wan to know more...