I put a turnbuckle on my '01's turbo last Monday. Tuesday on the way too and from work, I noticed a vibration that was not there before doing this. The vibe is only noticable at or above 70mph and is not related to the application of power (it's there when coasting above 70 as well). I can't think of anyway that this could be related to installing the turnbuckle and is probably conincidental, but I though I'd ask anyway.

Next step is remove the turnbuckle and see if it goes away. Also need to check the u-joints and wheel bearings. I just can't see how this could be related to the turbo.

 

Well, I was out again tonight and ran some more "tests" to try and pinpoint this vibe. The vibe does not appear until 70 mph, the frequency increases with wheel speed, vibe is independent of engine speed (verified this by getting up to about 75 mph and shifting into neutral and getting out of the pedal). I checked the u-joints and they all seem to be tight. Looks like I'll be checking the wheel bearings next.

 

That and also check your weights on your wheels a weight might have come off.