Some of the cheapo parts store biscuits are quite a bit thinner than factory. And of a lower quality. Replacing them with the proper thickness may move your header away from the box. You could easily make some shims to put between the biscuits and the k member. All you need is some flat metal, a cut off wheel and a drill. Personally, I wouldn't trust the cheap rubber mounts as far as I could throw them. I prefer solid mounts as I don't mind a little vibration. There are alternatives though : http://www.dodgecharger.com/forum/index.php/topic,13216.0.html