Hi modelman
I do not know if you are able to reprogram the ecu yourself, I would think not as there would not be a market for these 'superchips' however I have used a tunit module on our old 2.5 bmw diesel and it did make a difference giving it more grunt, some time ago I read a report that tried different performance chips and modules and they came to the conclusion that the replacement chip in the ecu worked better but I cannot verify that. I now have a 2.5 dse and was hoping to fit the tunit module onto this vehicle, as it clearly says suitable for BMW/RANGE ROVER but when I contacted the company (Tunit ) they said it would not fit and they would not send me a copy of the instructions to fit it even though it came from them apparently they require the original invoice as it is against company policy to give out copies, my point is to make sure that whatever you fit it is suitable for your vehicle regardless of what the unit might say, I am now in the process of contacting trading standards over this misdescription of their product. I hope this has not put you off, because these chips can make a difference, just do your research