Hi Phil,
Octane doesn't change the relation. All octane is (in simple terms) is the ability to resist pre ignition from heat.
We received your email and wonder if your car is using a different part throttle map. There are a few things to ensure.
1) Make sure your MAF is installed and functioning properly. We have a trouble shooting guide in our manual section.
2) For the sake of using the proper tune, make a change to your WOT fuel table, save it, and load that tune in all 4 positions so that you guarantee you are using the tune you think you are using.
3) Make sure the values you type or adjust are sticking. Simply hit enter after typing a value. Save the tune, open it again and make sure the values you entered are still there.