I also did my seat "humpectomy" by myself. The two humps are cut away individually, leaving the middle piece of the seat tub for support of the new foam which was stacked from two layers of rebond I got as a scrap for free. A washer fluid jug provided the two pieces of plastic to support the foam from underneath. I didn't even need to glue anything in as it just stays by itself. Even just two layers of foam is a little too thick so I may fine tune that some more later. The fabric store had a nice selection of vinyl that matched the seat pretty well so I cut out 4 circles the size of the washer fluid jug cap and glued them on underneath and on top to cover the holes with some special vinyl repair glue. It seems very durable so far and save me the $120 that the upholstery shop wanted to do the mod.
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