PRSWILL

This may seem obvious- but how much have you been driving the car? If it's been sitting for weeks, there may be some flat spots in the tires and getting the car out and running it for 50-100 miles will take them right out. I have had a slight vibration with certain tires after taking the car out of storage, but it always goes away after a nice long drive.

kkell3232

Here's the verdict:


As you can see two were out of balance and the other two were flagged as being a little high on road force. The high speed vibration is now at least 50% better. What's left is minimal/tolerable and I would attribute to the stiffer sidewalls and RS engine mounts- sound plausible?
The car is driven fairly regularly (ie weekly) and at healthy speeds (for the car not me) so don't think the tires are flat spotting.
This was a helpful lesson in what a difference tire selection can make and just how finicky the car can be if the balance is not well done. Thanks again for all of your input.