With regards to fuel consumption, you may not get better fuel consumption from premium but you may benefit from the additives they put in it. As we discussed in Sydney, the 2AZ-FE won't 'perform' better on running on Premium98 all the time; but it would be beneficial to run it once every 4th tank or something like that to help clean up/keep the engine clean. I'd personally run it 1 to 2 just to keep the engine clean, although WHEN you get boosted you will want to run 98 ALL the time :) If you wish to reset the ECU do the following: 1) Remove the negative battery terminal and leave it off for ~30mins 2) Put the battery terminal back on 3) Start the car and let it do the normal startup (Airbag lights etc), run the car @ idle for 10mins 4) Remove the negative terminal for a 1/2 a minute 5) Replace the negative terminal and off you go 6) Drive Go nuts, the car will learn your driving style!