Yeah, I've had this truck tuned for 91 octane before, but only because I was experimenting with ethanol free fuel and that was the only grade available in my area. Spoiler alert, ethanol is not the devil. I got way worse mileage on 91 ethanol free than I ever did on top tier 87 with up to 10%. Justin at Black Bear has told me in the past that I'll definitely pick up some power on 89, but anything more than that is a waste.
I like the TCC lockup and shift points where they're at, so I won't be messing with those, and my speedo is within 5MPH at all times when checked against GPS. Probably just have Black Bear bump the timing a little and set my (now useless) factory PCM up for 89. That way I can always swap between the 87 and 89 tunes as needed/wanted.
I like the TCC lockup and shift points where they're at, so I won't be messing with those, and my speedo is within 5MPH at all times when checked against GPS. Probably just have Black Bear bump the timing a little and set my (now useless) factory PCM up for 89. That way I can always swap between the 87 and 89 tunes as needed/wanted.