I knew the ebay chips comment would make someone reply ...lol... Didn't think it would be you Ken.
The ebay chips seem to make more power- if it's real or not on a dyno I cannot attest. I've used them on two cars now, and I would do it again.
Is it possible that someone selling ebay chips may have the maps right for more power? I mean, couldn't they copy what the current "updated" chipset does???
I sell used parts

what works best is best left to guys like Ken.
BTW Ken, your tensioner upgrade is the best thing anyone can do to a 928. Bravo.