Did they do a load balance or just spin balance. Is it speed sensitive?

Loose warn parts would give you shakes after a bump.

For a problme like this I would normally swap wheels front and rear but I don't know if this is possible with 18 and 19s. I would also test after removing the steering dampener. This might make the shake much worse and perhaps easier to identify. Think this last one over carefully because I have no personal experience of the risks.

Just a side note. I don't understand all the praise on replacing the steering dampner. I have owned many cars from the 50s and 60s that had worm and sector steering gear and not one had a dampener. If the wheels and tires are true and balancced what do you need to "dampen." That said, if my CF gets a shake I am going to get load balanced and then replace the dampener. I am curious but not stupid.