I just bought a 3.91 rear diff for my 2010 6MT and am trying to find a handheld tuner that:
1) has gear ratio speedometer correction in it's options, and
2a) will allow for gear ratios to be input as an open variable, or
2b) has 3.91 as a selectable ratio.
I don't have any performance shops near by that do custom tunes. I live in what some people call "fly-over country," plus, I'm going to remain basically stock and trying to keep cost down, so even if a shop was near by, I'm trying to avoid that extra expense if a handheld has the options in it already.
I have not installed the differential because I don't have this problem solved yet. So far, even the owner's manuals of various tuners don't go into enough detail as to actually address this question. I have even looked at manufactures' websites and forums and I have not found the info there either. An unnamed manufacturer answered my email by saying it "should," have the option, and if not, they would write a custom tune for me which included it. This isn't really encouraging since they couldn't even tell me if it did or not, but "should..." I guess he couldn't be bothered to go fire up one of his products in the name of some sales.
So for those of you that own a handheld with the gear ratio speedometer correction option, and an itch to help another Camaro in need, could you connect up your tuner and look through the options for the gear ratio and answer back with:
1) make and model of handheld tuner,
2) if ratio is adjustable by an open variable, as in you input the numbers, or
3a) if ratio is adjustable by selecting from several preset values, and
3b) if 3.91 is one of them?
Thanks in advance for this. I can't wait to put this issue to bed, install my diff, and actually go enjoy this upgrade.