You probably have the theory right on the VGT. I thought it might act like an exhaust brake, building back pressure. I would think the main idea is how much real slowing do you get. If we were sided by side on a steep hill on the freeway with our 36's we could put them both at hi at the same speed and see if mine slowed a lot more than yours. Of course we would have to be somewhat even in total weight to get a feel for that. But you probably remember pretty well what your '06 felt like.
I had talked to Keith at RTS about having the 1.75 mod done to our coach in January when I have them flush the brake fluid and clean/lube the pistons and calipers like they did last time. He said at that time they were still working the 1.75 mod and had not got it working the way they want it, but were going to try some other ideas. So I guess they decided to go back to the 2" while they worked some more on the concept.
I'm not unhappy with our brakes, but thought if that MC mod works, I would be interested in doing it, because more braking power is usually always better.
Will be interested in your further progress. I'm going to get the coach back from storage tomorrow and get ready for my annual 6 weeks of deer and elk season. Nothing an old forester likes more than being out in the woods each year during hunting season hunting the timber and scouting the fresh clear-cuts. Maybe by the time I'm finished you'll have that brake mod figured out!
Former Owner, 2006 36MDDS
2010 Arctic Fox 22GK Travel Trailer
2007 Toyota Tundra