A few years ago I installed a MB Tex kit over my original horse hair pads. The seats looked ok except for a few wrinkles where the horse hair deteriorated. The new seats looked a little "deflated". Now, plans have changed. Switching to leather and chose to go with the new foam. New cars use foam and I expect the foam should hold its shape better over time. However, the foam replacements have not been on the market long enough to form an opinion. The pads I bought came from a German supplier. After opening the shipment, I found one piece that needed replacement because the foam injection came up a little shy on one side. They sent another no questions asked.
Keep in mind, there are slight differences in the seat cushions between earlier and later cars. I think the foam replacements are only for the later style seats. They will fit the earlier seat frames but I am not sure you would want to go that route if you have already invested in your upholstery.
