+1 for superchip
I too had an E53 3.0d X5 and E60 530d done by Peter via Bluefin module. Performance gain is very noticeable and the turbo kick is much stronger. Economy is actually improved slightly for both of the cars.
If u want a good tune, superchip does have an excellent product at such a great price. DMS automotive wants over $3000 for their tune which is about what most people charge in Aus. I recently also tune my Q7 4.2tdi with peter and has positive outcome so I can back what the OP is saying. It is a no brainer to go with Peter @ superchip for proper remap.
Too bad you are not in Brissy, we should meet up for a quick spin!
