'07 Corvette C6, at 4800 ft altitude ... help!

[Dooce]

After hours of searching I'm not confident I've found the answer I need. Appreciate any help.

Background:
Predator U7194 with firmware revision 9r07
Corvette C6 operating at 4800 feet
Only 91 octane gas is available here

Answers to ANY of these questions would be deeply appreciated:
1. What are the tuning differences between the 91 and 93 octane tunes -- esp. spark advance differences for this firmware? (Or how do I find out?)
2. Can I safely use the 93 octane tune while running 91 octane gas at this altitude (4800 feet)?
3. What tuning specs do I lose by installing the 91 octane tune instead of the 93 octane one?

Thx.
Bill (waiting hopefully )

[mikel]

1. About 2* of spark at WOT. (log it and you can see yourself)
2. Not the best idea, no....but altitude may help.
3. Again, you'd just lose 2* of spark advance at WOT.

[Dooce]

Thanks Mikel ...

You've saved me some trouble. Before my post I'd installed a 93-octane tune with spark advance retarded 3 degrees from their defaults. From what you've now said I realized that this tune was *worse* than the 91-octane tune which I have since installed in the car. |Just returned from a test drive and all seems to be well.