Yes - broken turbo
The intake impeller nut had come off and jammed into the fan blades. Could have been worse I guess
Wimmer correctly diagnosed the issue with the turbo...and then gave me an additional nice bill for a 'smoke test' which I hadn't really asked for. Language barrier meant they were not motivated to get me back on the road same day even though I could see they had a spare turbo on the shelf (standard K04).
But any way, car came back to UK and now fixed and back on the road.
My adventure with slicks at Spa remained unfulfilled. Last time the gearbox broke before I could try the slicks, this time the turbo before I could get any heat in them....so operation sub 2.40 will have to wait until another time! Think from now on the XBow will only go as a spare car, I cannot trust it as the only car at a European track day. Wish I had also taken the GT3RS at Spa - was going to but backed out at the last minute.