I have the same problem. very bad vibration at 50+mph. I can't really go over 60-65mph or it feels like the steering wheel will shake off! But the shake comes and goes even when maintaining a particular speed. The tires aren't out of balance and the wheel bearings are in good shape.
I went over to my friends shop,
http://www.mainstreamperformance.com where they do a lot of 2jz swaps... They put it up on the lift and we looked at everything we could think of. The things that control the caster (tension rods) - the bushings were fuxord. And one of the steering rack pieces (tie rod) was really loose as well. Of course the balljoints for the tie rods were shot too..... So... I don't want to spend too much $$$ but are the tein pieces worth the loot? I've seen so many different mfr's of these parts, which is a decent deal? I take it the $80pr for the tein inners and another $80pr for the tein outers doesn't come with the spherical bearing balljoint? Or does it? And iirc, suspension techniques sells the caster/ tension rods for around $100 with spherical bearings?
Are these ok for the streets or will they rip out the mounting points on rough surfaces/ street driving?