Yeah i am mate, its always showed not great oil pressure, normally 0.5 ish at idle when hot, and 2.5-2.7ish when warm at 3k.
From cold it shows 3 bar ish on idle, and 4 bar at 3k
It raises a little at WOT, but as soon as the revs get higher it starts to drop off, which iv not seen a mk1 gauge do before, and iv now had 2 pressure sensors and 2 gauges, but as said il be checking it with a mech gauge.
As said im keeping my fingers crossed it's a gauge fault as I know they are not reliable, but as it looks to be dropping pressure I can't ignore it.
Might explain why iv always thought the top end sounds a little noisey mind