well the basic repair is the same principal as any bolster, although im surprised an r35 is having this issue? usually its on much older, much more high mileage stuff :s
if your feeling brave you can strip the seat down and repair the foam and then put it back together. Im not 100% on teh construction of the r35 seat but i doubt its any more complex than most (to get at the foam that is).
Its caused by the foam rubbing on the metal frame that supports it, eventually it rubs through and the result is what you see here
i recently did a huge overhaul on a couple of recaro SR's (sr2 and sr3) and whilst a pain in the ass to do the whole thing, one bolster wouldnt have been difficult
here you can see the tear in the bolster thats been caused by lot of repeated impacts, or lots of small impacts by a heavy set person
on the inside of the recaro foam, there is a small patch of particularly hard material that sits against the metal frame (probably why they last so long) i reinforced this with denim when putting it back together to try and stop this happening in the future.
The foam can be repaired if its not too far gone and the shape of the bolster can be brought back to normal with the use of a wallpaper steamer (you tube "foam seat repair steam" and youll see what i mean)