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Excuse me for the ignorance but I am only relatively new to this whole tuning idea.
Running a standard 2007 Impreza 2.0L SOHC, and always run it on either E10 or regular unleaded since I got it, however recently have always made a point of only using 95 or 98 octane.

I have heard that engines will get no benefit from premium fuel unless they are tuned to properly run it. Is there any need to tune the ECU for a 95 octane fuel, and will this provide any more benefits than what I currently get?

Unless you have a turbo motor, who ever is telling you this, either wants your hard earned money or has been fooled themselves.

Your motor and ECU are designed to run on premium fuel not E10 or regular unleaded. the motor will run on E10 or regular unleaded but not as well or efficiently.

You can reset your ECU which will ensure you are getting the best out of your engine.

NOTE: Do this on a "cold" engine. Leave it sit overnight and do it in the morning.

1. Disconnect the negative battery terminal cable for 45-60 minutes.
( I leave mine overnight)
2. Reconnect the negative battery terminal cable.
3. Turn off all your accessories.
4. Start the car, but DO NOT touch the throttle at all.
5. Let the car idle for 10-15 minutes, or until the car is at normal operating temperature. Again, do not touch the throttle.
6. Turn the ignition key to the "OFF" position.

from this thread

showthread.php?t=14372

TOONGA