Yep, I had my done by an independent, who custom remapped the Gearbox ECU and upped the pressure that the cc pump runs at.
I know MAF has had something much the same and he is over the moon with it.
I was so impressed when it was flashed on to my 4200 Spyder that Zag now has, that it was pretty much the first thing I did when I got the GranSport.
Having had both DBW and GECU, I would go the later every time.
Matt who did you have instal the GECU upgrade?