Bumping this back up, how much do the HKS Kansai rails lower the overall seat height?

And do they work with GC8 seats?

I've just put a weld in 6pt cage in my GC8, and the stock seats are too high (I'm 6'1") hence I need to lower my driving position so I'm actually lower in the car than the cage :P

Any other options? What seats have others out there gone for in GC8's with cages?