Ready Go
Ram Guru
I believe there is actual fuel & ignition changes also.There is a tune difference in T/H mode; that's why the button exists. It deactivates MDS, changes shift points and in my truck seems to set the gear limit to 7th gear. I will use it even when towing a light trailer primarily because the it downshifts earlier and noticeably improves engine braking.
7th gear is held, but it will shift into 8th gear at around 65mph if not under load.