Eurofordfan, they are solid as a rock. Part of the installation/adjustment calls for pulling and pushing on the towers. And also every couple hundred miles.
The Q-clips that go under the door rubber are very thin. I took the racks off after 4 days, 500 miles and camping in the back country (OK, car camping). Washed the car and looked VERY carefully for any evidence the racks were there and could find none.
Candy Blue SE HB, 6sp Auto, Sport Package for the wife
Sterling Metallic SE HB, 5sp manual, Sport Package for me