It was a common thing on motorcycles to reshape the foam and then recover the seat a few years ago.
Supposed to be easy to carve seat foam with an electric carving knife
It'll work, but for every inch of seat foam you shave, you'll have to cinch up the upholstery an equal amount.
Translation?
Unless you got mad upholstery skills, your seat bottom is going to look like babboon ass.
Ever see the thigh bolsters on leather seats in a fat guy's car? It's going to look worse than that. And by fat I mean so fat that he has to back into the car ass first and the thigh bolster ends up getting rolled up under his ass.
and don't VWs use sisal instead of foam?
I know my ex's VW had fibers poking through the seat that would stick you.