Thought I'd update this, but after the fun at SC and a slightly improved map, going by stats I've found through various online resources, with the output of my car being at:
189/190 bhp and 315lb/ft torque
this puts me on near enough on par with a BMW 123d (201bhp and 295lb/ft), which has a 0-60 time of 6.8, so my GTTDI must be close if not 7secs, which makes me smile