I took it for a drive and and couldn't feel any noticeable drop in power in that rev range, in fact the turbo felt like it came in earlier then that graph shows. I did notice a slight drop in boost in that rev range thou..

Got a rolling road day at TOTD on 6th Oct so will see how it performs then, maybe a silly question but could it be anything the rolling road operator has done as it was only a power run wasn't any tuning done etc