So I popped for the HP tuners and the first thing I was going to do was adjust the tire/ gear ratio to bring up my cruise rpm (even though I am in the middle of GM's recommendations). Pretty disappointed to find the TCM is locked. Yes I understand I could send it to HPT, WTF! Anyone else running the 8L90 transmission have feedback on their cruise rpm's?
Last edited by vet57air; 06-10-2021 at 02:18 PM.
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