Not that you should, but on any decent 93 tune you could probably run 91 octane and drive it like you stole it. With driving that avoids WOT you'll be absolutely fine.
I, and others have run race fuel programs intended to be used with WM or 100 octane on just pump 93 for various reasons including crappy pushloc connections. We've pushed the cars hard and the motors appear to emerge unscathed. Once I ran the car wide out to redline in 5th with VCDS connected and my WM unknowingly disconnected on APR 100 octane. ECU pulled maybe 7.5 degrees of timing.
