Ok so I have replaced all the speakers in my car amp etc. It is nothing real loud but sounds good to me, all except it seems at certain frequencies fairly loud the 6.5 drivers in the door seem to rattle the inside of the door. This is obviously annoying and I was wondering if some of that dampening mat stuff would help. I think I saw parts express sells some fairly cheap. I have a crossover which I normally leave at 80 hz but if it starts rattling I bump it up to 120 hz and it seems to go away but doesn't sound as good to me. Also if anyone has any advice on setting EQs in cars I would appreciate it.