91 octane tune is totally safe on 93 (but not the other way around). The 93 octane tune will give slightly more power/torque
Run 93 if that’s what’s available in your area - although the car will probably save itself and be fine, don’t ever try to run a tune on 87. At best you won’t see an improvement in power, at worst you can hurt the engine.
For ignition corrections, positive is good. A little negative is okay. Really negative is bad. One cylinder more negative than others is really bad.
Youre unlikely to have issues with ignition corrections with an OTS tune unless there’s something physically wrong with your engine. Corrections will float all over the place during operations.
A more useful value to keep an eye on if you’re concerned is OAR. This represents how good the ECU thinks the fuel you’re running is and how much across the board ignition correction it needs to do. -1.00 (negative) is good and where most tunes, especially OTS tunes are designed to run - meaning most of the time the ECU is allowed to advance timing as much as it wants.
If OAR approaches zero or goes positive, that’s bad and it means the ECU is dialing back timing and power/torque to preserve the engine. Either something wrong with your engine or you got a batch of bad gas from a cheap shitty gas station or filled with regular 87 or something (either by mistake or you’ve been had by a cheap gas station that cheats selling regular as premium)
But really, drive around for a bit, make sure OAR stays at -1.00, then put away your Accessport unless you’re trying to diagnose an issue like overheating problems.
