Thanks for the explaination powers1.

I thought that most of the units would remap the fuel table rather than just use a fuel pressure hack.

How does the tunit work? Does it remap the fuel table by intercepting the fuel pressure sensor so only the high load parts of the table are modified? Will the standard engine management log any errors about air/fuel ratio that would be obvious at service time?

I have a fair amount of experience building and tuning petrol race engines with Motec and other computers. I've never been a fan of piggy back systems. I havent got my head around the fueling systems of modern diesel engines yet.

Chris.