That would depend on how high or how low you want to sit. Get a bucket seat, take out your old seat, get some pieces of 2x4 or something, and mock it up. Sit in there and see where you want to be. If you need to remove the riser, then that's what you'll have to do. If you can build on the riser, etc. Some folks like to tear everything out and start with a flat surface.
