premium fuel for H6 3.0?

Aren't there different scenarios? I'd imagine that a normally aspirated higher-compression engine designed for premium would be tuned for premium at all times.

If it's a turbocharged engine, cruising at 50 MPH in 5th gear on a flat surface, it might not make that much of a difference. If there's no boost, then it's essentially a lower compression ratio engine without air being force-fed. The timing could only be advanced so far, so would the sensors detect knock with 87 (R+M)/2 octane unleaded?

Of course I'm not taking any chances. My WRX gets nothing but