I've been trying to tackle the problem of how uncomfortable (painful) my leather seats are. Sitting in them for more than 30mins starts to wreak havoc on my lower back. I've considered switching them out entirely for an aftermarket set, but figured I might as well try a foamectomy first. Here's some things I learned from my experience:
When peeling the covers away from front of the seat, use caution. The velcro attachemnt is very strong, but the backing is glued to the seat foam and will rip off very easily. Also, don't attempt to pick the foam out with your fingers. One such area I screwed up is circled.
The seat covers and foam should be fully removed from the seat frame before starting the job. I used a dremel to grind away the foam and this created an absolute mess that got into every crevice of the seat. Problem was exacerbated by the fact that my hand vacuum is a POS.
I grinded off the hump at the edge of the seat where the thighs rest. Never liked how it elevated my legs slightly. Tall people looking for more headroom could probably remove some foam from the middle area to sit deeper into the seat.
I removed a lot of foam from the center section. The side bolsters feel a little bit tighter now; like I'm sitting more between them instead of on top of them. Also removed the foam bar that was pushing into lower back (circled). Oddly enough, removing that piece has made the seat less painful now (still wouldn't call it comfortable) and would explain why JPM's lumbar bladder never did anything for me.
Only downside is that, of course, the leather doesn't have as tight a fit anymore. A small trade-off to make some terrible seats tolerable.