i THINK melv that 255 is just the data value and can mean fookin anything...
it's the ECu itself (ie the other million chips in the box) that knows what 255 means
please correct me if i'm wrong or going off on a tangent...
also after reading that i'm DEFINATELY getting off my arse and sending you my turbotechnics DCU as i'm confident you can decode and re-map it! infact i'm gonna put it in the post RIGHT NOW :P