Going by the number plate: was the builder located in the western suburbs of Paris?
Actually I was hoping the plate would throw people, it's a Dallas, Texas plate - not sure what it's doing on this car - but oko was straight on the ball with the French connection. I don't believe they're Parisian, no, but that matters not because...
Hrubon ?
That's spot on!
I honestly expected this to end up in the black hole, I've not been able to find a single mention elsewhere about Hrubon's fettling of Porsches but you tracked it down masterfully!