Have you already put the speakers in your car? If so, how much rattle do you have? I have a full set up in my 97 tahoe and I don't have any dynamat anywhere. I have 2 12in punch p2 running 200 watts each and the only rattle I get is from my change door. Keep in mine that it is an american made piece of junk and I off-raod the hell out of it and that has put a lot of rattles in it. You are going to be able to tell the difference between having and not having sound deadening material but unless you are an audiophile and have a superb, high output system, I say hold off until you save more money. See how you like what you are putting in first and then go from there. I was going to spend a bunch of money on sound deadening after putting in my system but once I got it in there, it sounded fine to me. Make sure you install your speakers correctly and mount them firmly, don't skip on screws and stuff.