ive had my subs for about a year now. theres a few rattles that just started a few weeks ago. i dont know if its due to the cold, or the subs. i normally dont have the subs up very loud, but every once in a while ill blast them. theres one rattle in the drivers side door panel somewhere near the window. theres one in the steering column, the thing that you press to honk the horn, but thats due to a new steering wheel that ford put on wrong. and theres one squeek, on that felt piece that covers the trunk in the zx3
i have 2 10s in the spare tire hole of my car and even before i had them there, they were just in a normal box and the trunk lid rattle a little but the spare tire rattles alot even after dynamat but the lid stopped
i haven't had any problems with my zx3, i have a single 12 with almost 400 watts, it's 100 times better compared to my brother's car and my friend's cars that have subs in it. if you have any problems check out fatmat sounddeadner ( www.fatmat.com ), the price is alot better than dynamat for the same effect. if you really wanted to get some cheap stuff that would probably do just as good is "peel and seal" from home depot. it's roofing supplies but i think it's assfault based so it might smell a little if it gets hot. but if you have a sedan and you line the trunk with it you shouldn't have any problems with that.