If the Windrestrictor is installed properly, there should be no tearing of seals or leaking at all. It's been 2 years or more and we've not had any calls at all regarding this.
If there is a concern about the weather stripping moving too much or the trunk not opening it's because the product is not installed properly. Please give us a call so that we can run over a check list to make sure it's installed right.
The screws have to be tightened down snug, keeping those spacers away from the fabric, and the trunk seal....
But don't over tighten. I usually tell people, when you see the acrylic start to press against the rear panel right around the screw area then your tight enough... any tighter and the acrylic may break....
the warping is an issue though for people who choose to leave theirs on with the top up... If you are leaving your top up for periods of time and it gets extremely hot then it will begin to form to that back window.. we've had people say that they like this effect. But it is a disclaimer we give with all of our instructions as of several months ago...