[racer_d]

My general understanding is that the Power Steering is a weak point with Boxsters that are track driven (and might be compounded by oversized "sticky" rubber). But, as you've noticed when checking the level of the PS fluid, it sits at the top of a very hot engine bay. Combine that with the line placement and plastic material and failures happen.

I know several who have added a small P/S "radiator" up front to help cool the system. Others have used heat resistant wrapping on the lines in the engine compartment to shield away some of the heat.

Perhaps a combo of the two given your desire to time trial would be the appropriate measures to prevent further failures.

It is possible that the pump has been damaged since the system was run "dry", but I am not sure how you can tell.