I really didn't notice any power loss myself but I'm sure that has a lot to do with my driving habits. I very rarely put the skinny pedal to the floor for any reason and I'm usually never more then 5MPH over the speed limit. While rock crawling I'm always in 4LO and never once been in a situation were more power was needed. In fact I find spinning the tires requires very little effort. I know what your saying I've seen guys on obstacles with there foot to the floor and they weren't moving or spinning there tires LOL. I would imagine that it would take much bigger then 35's to cause this on the 4.7L in while in 4LO. I'm guessing a new TC would solve this if your getting something bigger then 35's. IMO 35's would be the max for all around use.