I didnt drive it, but went in it. There does seem to be very little power low down (off boost) but when it comes in its fine.
The TDI graph looks quite close to others with the same turbo although again it does seem to be lacking power very low down.
Changing the exhaust cam had little effect on the spool, it just seems to be a sluggish engine.
If you dont rev it high enough when you change gear it falls off the power band, which is strange for this size turbo.
I will have a measure of a stock head gasket Chris as I have one here, just to make sure.