Your ECU will learn to adjust the AFR such that it is running stoichiometric during closed loop fuelling. It uses the rear O2 sensor to adjust the fuelling to always try to maintain a lambda of 1, and it will store the value of any increase or decrease from the fuelling table in the RAM. When you go into open loop (like at WOT, or under boost), it will apply that same amount of correction to the fuelling table.
For example, you fill up with Esso 91 and your ECU learns that you need a certain amount of fuelling when you cruise around. At 1/2 a tank, you fill with Husky 94 with 10% EtOH and now your car needs 3% more fuel to reach stoich when you cruise. It stores this in the RAM, so that when you enter open loop, it automatically adds 3% more fuel than what is called for by the basemap.
To top this off, your ECU has some leeway with the timing, and it will try to run as much timing as it can before it decides there is knock. The Husky 94 is the most knock resistant pump fuel we have available to us in Alberta, and should allow your car to run as much timing as is called for, providing your basemap has reasonable timing, boost and AFRs.
The short answer is, you can run Husky 94 or mix it up if you want. It may take a little while before the ECU learns the new long term fuel trims.
