90 octane tune

[Jaycin2]

I'll start of by saying this is my first post, so forgive my noobishness… I am here to learn more about my 2015 ZL1. I live in Alaska so my access to higher octane fuel, dyno, etc... is very limited.

I have these mods: 2.55 upper, Cold Air inductions CAI, 63LB injectors, Kooks LTH, Cat-delete, ZMAX ported TB, Borla S-Type exhaust, 90 octane tune. 90 is the best I can get in Alaska w/o mixing race fuel which can be hard to come by and ~104 is about $20/gallon when located. My car has 8K miles.

My car was tuned on a mustang dyno. This is my best run, but the tuner didn't print the entire curve or let off early, not sure which. 517HP/558TQ at about 5600. The car pulled timing at 4200 and slowly fed it back. Tuner said he was seeing an ignition issue at the low end only at about 2800, then it goes away. He recommended a plug change, which I have since done. The plugs were orange, from Torco I imagine. I don't plan on using Torco any more. The oxygen sensor was as the color of an orange marker. Tuner said it was reading fine, however.

My questions are:

Should I be concerned given the 90 octane tune is looking like this or am I overly cautious?

Given the lower octane are my numbers on par with the mods?