I am installing 2 subs in my 02 camaro but I am having an issue. I dont want to replace the deck right now so I am just hooking it up with a line inverter. I have done this on my other vehicles with no problems. I hooked them into the very back speakers but my problem is that when the car is running the speakers have a constant thump. If the car is off then everything works perfectly. I have been playing with my ground wires and still nothing will work. How can I fix this? I dont want to put out money for my new deck yet. Thanks and please help.