Here are my 2 cents..
I5 3.7, 35" tires, air dock, and a lift, everything else stock
I can still cruise at highway speed up hill at 73-5 mph since my speedo is not program for the 35@s no problem. IMO I only had to RPM pass 3K if I'm going slower than 60 or let the speed drop. If I keep momentum and speed there's no problem. I can still cruise in 4th gear going up hill at not more than 2,500 rpm at 70mph no problem. With the truck pack with all of my gypsy camp and what knot...only time I have problem keeping up speed is when the truck is fully loaded with people and other scheiße.
Torres
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you."
-Friedrich Nietzsche