The old bus had now done over 120k miles which isn't much in itself, but might be a lot if I wanted to get it mapped now.

I would expect the clutch to go pretty soon aftwards but this is a consumable *cough*

Is there a point in an engine's life where it's not advisable to map?

I had my PD150 Leon mapped at 100k. As you'd expect, it started to destroy the old clutch within about 5k miles, but I'd expected that (maybe not quite so soon!). I sold it a few months ago on 134k and it was still running perfectly, never missed a beat or had any mechanical issues.

Not at all, mine got mapped 4k miles ago at 140k and I've had no issues

I would imagine the life of the clutch would depend on the smoothness of the map and the way you drive the car, ie don't boot it in too higher a gear. Shark maps are said to be nice and smooth.

Edited 14 July, 201114 yr by Jim H