I have modded many seats and always to add more lift to the front for more grip when on the brakes, etc....but I also like my seats to be as low as possible at the same time.
Depending on your body type of course this can also reduce the weight on the tailbone as more if spread across the legs making for long drives being much more comfortable.
I have had to open up seats on some vehicles to remove some foam from that area and it helps me a great deal.
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As long as you have enough thread engagement you can move them to your liking, front, rear, etc....
For aftermarket seats I usually end up making my own mounts to be lower, angle better, lower weight, etc....