Or velcro.

 

If you are considering aftermarket seats with large bolsters, consider that the bolsters are points of extreme wear upon entry/exit. Leather may not be the best material for this kind of wear. In my own experience many years ago, my heavily bolstered leather seats wore through on the bolsters at less than 50K miles.

 

So in a follow up to my question. I have identified 3 seat-back configurations up to 2010. Can i assume the XKR-S is a fourth? Is ther a fifth?
Do any listed offer a significantly better side bolster?

Vince

 

So I found a solution that drastically improves the seat's ability to hold you in in hard cornering. You have to completely deflate the lumbar support. This allows you to sit deeper into the seat. Then when you inflate the side bolsters, it provide much more support!!! Problem solved!