Yeah not to much though
The fairlane they were happy with a crush tube welded into the pillar with the head of the bolt protruding externally.
And the cloud 3 rolls royce I had to add a brace internally and use an approved seat belt thread plate thing .. initially lvvta wanted us to add extra structure into the roof rail and tie the 2 pillars together through the roof with extra support etc which was nuts. But the certifier we use pretty much told them to pull their heads in and we came to a more sensible solution