yeah balance the wheels then don't worry about it, it could be 1093741723947237 things. Mine does it, I think the CV joint is going, and it got better when I replaced the rear struts (blown) with new ones but not perfect. Bascially what i'm saying is tracking down this vibration after very basic stuff (alignment, wheel balancing) isn't worth it. I looked into it a while ago (search, you'll prob find it) and it has the potential to be SUPER expensive and yeild no results. It could be engine mounts, suspension bushings, struts, bent control arms, wheel cupping, wheel balancing, alignment, TIRE CHOICE, etc. as long as its not so intense as to be obnoxious, i'd just let it be. What I would look at, though, is that cross member....

vandy :thumbsup

P.S. i've heard aftermarket rims are incredibly hard to balance, and seeing as you have them, that may be the problem...