I have a 2006 v6 6 speed sedan. I bought it about 5 months ago, and ever since I've owned it I have issues with vibrations but only at highway speeds. Starting around 70mph, the steering wheel begins to vibrate, and it gets worse up to 80mph, where it becomes quite annoying. At more than 80mph, the vibrations persist but they don't get worse. So far I've done the legend caliper upgrade with new 6 speed coupe rotors (old rotors were warped), rotated the tires, put 2 new tires on the front, and got the tires balanced. None of these changes got rid of the vibrations completely, although one of my tires was definitely bad because changing the front tires helped a good bit. I do need an alignment, car pulls to the left a bit. Might that cause the issue? I just don't know why it would drive fine at every speed under 70mph, and then start vibrating at 70mph. Suspension seems fine, no issues other than the vibration.