I have an almost completely stock 1999 Suburban C1500 with 3.73 gears that I’ve 411 swapped from a 2001 Express 1500. I was able to read the bin with PCM Hammer, and use TunerPro to change “performance” mode from data bus activated to C1-71 pin activated. Looking at the tables, the performance mode isn’t really much different, and that is consistent with my post-write test drive.

Does anybody care to share their proven tweaks to make tow/haul as noticeable as it is in the newer trucks? Is there anything else I should tweak to get the full advantage from the 411 swap? Thanks.