And here I am 8 years later with a similar issue.
Wheels, tires, shocks, wheel bearings swapped, control arms, ball joints, CV axles, inner CV joints, tie rod ends, strut top mounts, alignment - you name it - but still shakes.
Have 034 top mounts and they are alright. Also have 034 dogbone mount and the original rubber bush in the subframe.
Also have solid rear (on the front) TT/RS rubber bushings. And wavetrac LSD.
I'm inclined to believe that my drive-train vibration might be a contributor here.
I might be having a failing fly-wheel.
For some reason it is more pronounced on the right wheel and has a vibration pattern, smth like trr-trr-trr-pause and again.
Gets worse with a slight steering angle. It is noticeable on straights, and non-existent when wheels are turned for more than a bit (at the same speed).
It's a pain to diagnose, but it's currently not that bad and subsides approximately below 75mph. Do want my perfect car back though.