new owner ecu upgrade

Have just returned from 3620miles in europe with my td5 2005 towing a caravan only had car a week before leaving so a good test would like to know owners views of ecu upgrades etc do not want to hit mpg to much
thank you

Had a 1999 Disco II ES TD5, changed chip and bigger intercooler, 185BHP plus about 80 ft lb more torque. MPG about 30 to the gallon. Pulled a 14' trailer loaded 3.5t. didn't slow down on hills like it used to. Drove to the Alps several times in it, 4 up, loaded, top box, cruised at 100mph all the way, no problem. Cost about £1100. worth every penny, V8 performance, Diesel economy.