I honestly didn't read much into how it works, and thought that it was going to target the boost pressure rather than duty cycle.

I have the Jaycar IEBC too which I used on the 1G, so I have had epic amounts of experience setting duty cycles since that thing can be a real bitch to set up on the street. You really need to be in a high gear, and you need to go through the whole rev range to set it up right. That said, you can get it on boost damn quick and hold it there until redline, no worries at all. I just can't be bothered setting the thing up again for the 1jz.