Sounds like a caster issue if you still have the tracking problem. C/C plates is the way to go. The bump steer kit is mainly for turning. Straight line driving is mainly a caster issue. Depending on how wide of a front tire you are running may also be an issue. Wide front tires will pull you into uneven road surfaces and not much you can do about it. If you get the alignment done, get a print out and post it.

 

I had caster bolts installed when the car was aligned. I suppose it's possible that one has loosened. I'll post the alignment sheet if I can find it.

 

Just because it is set in factory specs doesn't mean that it is where you nerd it to be. Toe and camber will wear tires out and keep the wheels from facing level and forward. Caster will affect pulling/tracking/turning. With a wider front tire it may be necessary to adjust caster past the spec to compensate. Just need a good alignment guy to make it ride right.

 

This may help explain.

 

I need to get the numbers but the caster was moved forward quite a bit as I recall. I do need to put some positive camber in though (on the right side). My camber numbers were -.8 for the left and -1.4 on the right. I was pretty pissed that they were that far off but the place said that was within their spec.

I will probably end up taking it back to firestone. They will end up saying I need camber bolts. Instead I'll end up installing camber/caster plates and in the end I'll probably still have the vibration.