When I had my 2015 2500HD I had the gain set right at 7.0 whether I was pulling my 40.5' 5er or 29' TT. With my current 2021 3500HD DRW the gain is still at 7.0.
From what I read years ago you don't want the wheels to lock up when applying the brakes. So when you set the gain, you take it to where it will start to lock up and then back the gain down a hair so it won't lock up the brakes.
Even though I have never had a problem, am I wrong?
Be safe -
2018 Cedar Creek 36CK2 (40.5ft)
TST Cap System (Tire Monitoring)
2021 Chevy 3500HD Crew Cab 4X4 DRW Duramax (replaced 2015 Chevy 2500HD Crew Cab 4X4 Duramax)
Curt A25 5th Wheel Hitch (replaced Demco 18K Auto-slide)