The Poadster, before fitting the MulFab sump, was 83mm...

The Plus 8 is exactly 100mm on its 19" wheels with 35% profile tyres and the sump is steel, not cast alloy.
It is, after 18500 miles, unmarked. (Unless the factory replaced it before sale....)

Peter,
66, 2016 Porsche Boxster S
No longer driving Tarka, the 2014 Plus 8...