I was messing around with the Tow/Haul button and noticed that on my truck (with the 3.55 gears) when the T/H button is on and the accelerator is mashed to the floor, at between 4000 and 5000 rpm the engine/exhaust has a completely different roar and more kick than when the T/H button is off.

Am I delusional or is there really a difference?

I thought the T/H button just held the gears longer to keep the truck in the power band area when towing.

 

From my technical understanding of how the T/H mode is supposed to work, you're correct in that it basically just delays shifts. It shouldn't change anything under WOT. But that doesn't mean that's necessarily the case. I'll have to go out and give it a try.