The ECU will be the same Bosch ECU used in all models though the tune will obviously be different to other engine units/sizes, whether anyone has tuned one...I wouldn't have a clue
Hehe - I keep learning stuff when you answer Craig :-)
I am assuming someone will have had a 1.8L tuned somewhere in the US - if so somebody may know the parameter location mapping. As you say the tune will obviously be different - and they won't have a 'base tune' to go from (if an i30/Elantra GT hasn't been done); but, of course, each custom tuned engine can be different depending on how fine the parameters are (and how much time will be spent).
HunterB - not that you have indicated going the tuning route... just an FYI (which you will get from the ECU reprogramming topic anyway) for tuning the ECU has to removed, flashed, re-installed - Hyundai seems to have locked down access... so it can't be done in real-time via OBDII, etc. ports