<but wha about th accessory wire that turns the amp off wen the car goes off,were does that hook up to?and when te car is off should the capacitor still b on or off?>

The accessory wire should be connected to the power antena wire on the deck/stock wiring. The capacitor should be connected inline of the main power cable from the battery and as close to the amp as you can. The capacitor just stores and releases energy, so it is never really on or off. Here is a link that will be able to help you out:

www.soundillusions.net Make sure and click on Tech Zone. There is a lot of good information.