There are always 2 sides to every story I reckon
Over 400kw, with Nitrous on a stock bottom end - what were you expecting? Like Beer Baron said, if CRD supposedly tuned your car stupidly lean, show us the graph that confirms it. And more to the point, did you not look at the dyno graph when they tuned it and check the AFR's?
I will believe it when you post the dyno sheet, because I dont believe that CRD would push a car with a stock bottom end so far and not leave a safety margin