Does anyone have experience with external Ecu tuning box which is plugged into the ECU. One company I have seen is Tunit:

http://www.tunit.co.uk/

Would like some info as I live in Chile and there are no guys would represent any of the major companies the remap your ECU, such as superchips or celtic tunning, etc.

the ones that i have had dealings with with other cars have been a bit rubbish imo... but they were for petrol cars, not diesel, so they maybe different.

cheers, david.