I upgraded my two-way power seats to 8-way power seats by swapping in the bases from an 8-way power seat. Now I have two manual bases that I don't need. I believe they can be modified and used to mount racing seats. I'd like to net $75 from selling both bases. They are heavy and shipping will be about $50 for both of them. Send me a PM if you are interested. You can find more details here:
Boxster Seat PartsThanks for looking.