ok i have a 95 240sx.. and im not sure what to do now.. i installed my alpine headunit recently and everything powers on but i get no sound.. i think i have a premium factory system that has a stock amplifer.. i was told to connect the amp turn on lead to the factory amp turn on in the harness.. ok theres only one problem there. i have no idea how to do it.. anyone have any suggestions? let me know, thanks in advance.