Yes, agreed - it's a small addition pre-turbo but still feels very noticeable (smoother is the word I would use). I guess it is from some increased fueling?
I can't find the more recent dyno's anymore (with Trevor comparison), but here is one of the earlier ones that I checked earlier when I estimated the extra 10bhp pre turbo.
On this dyno (pre full development of 3+1 of course!) the real boost happens around 1900, and Max torque at 2150 which seems inline with your observations.
As an aside, all of your comments and reviews (and no doubt feedback for tweaks to Andrew) of the DTUK really were spot on! Not that I ever doubted it, but it's transformed the car - and not just in a boy racer way (as fun as that is) but in smoothness and driveability. But I best shut up about it, sorry Fred!