Wow, Lars! Let's see if I can answer your questions:
First, the CAI was probably making your truck run lean. Most of the aftermarket ones "fool" the MAF sensor into thinking your truck is sucking in less air than it really is, so the PCM doesn't increase the amount of fuel to balance everything properly. Custom tunes CAN fix that and you'll be able to use your CAI again.
The Gryphon's 3 canned tunes are the same as the ones you find on the Edge, which is not surprising, since the Gryphon is a "rebranded" Edge that can be custom tuned. The tunes are:
0. Your truck's "stock" tune
1. 87 octane transmission only
2. 87 octane tow
3. 91+ octane performance
I don't even know why there is a Level 1 tune. It "firms up" your shifts, and that's about all. It DOES give you the ability to adjust for different tire sizes, gears, etc. too. But, Level 2 and Level 3 give you these features too. The fueling, spark setting, shift points, etc., in Level 1 are what your stock truck always had.
Level 2 is a "good" tune. It's really designed to pull heavy (2500#+) trailers, but most people find it gives them a much better feeling of "power" and it improves their gas mileage too. It's probably optimized for trailers in the 5-6000# range, but many people use it for daily driving too.
Lots of people like to use 91+ octane gas, and the Level 3 tune is written to improve the power band through the envelope while taking advantage of the anti-knock properties of high-test gas. It has an advanced spark, in addition to different fueling strategies.
The Level 0 tune is what you put back on to your truck anytime you take it to the dealer. You do not want him to reflash your PCM (which they have been known to do) if there is anything other than a stock tune on it.
Corey wrote an excellent explanation of the difference between "canned" and "custom" (and "stock") tunes here:
http://dygytalworld.ehost-services13...read.php?t=288 It will probably help you understand better than anything I can say.
In your case, since you live in SD, your average temperature is much less than mine in AZ. That could require a slightly different tune. You may be at a different altitude - same story. I pull a relatively light 3600# trailer, which needs a different tune than a guy pulling a 4-horse trailer full of hay burners.
I personally think 87 octane gas is the best choice, regardless of tune. I say that because unless you can raise the compression, you can't really take advantage of the potential of 91+ octane stuff. You'll get some of it through the advanced spark, but you're still letting quite a bit just flow out of the tailpipe. I don't know why your friends would say SD gas is crappy, maybe it is, but I don't see any reason for it.
Hope this was helpful!
- Jack