I love my 4.10 ratio in my YJ. I have a 4" lift and run 33" MTs and it is my daily driver and I off road just fine in it. Not a single problem. Since you have the 2.5L I would keep the stock 4.10 gears. That is just my personal opinion on the matter. As for gas mileage, you got a jeep, not a hybrid, so your gas mileage is going to not be good anyways, regardless of gearing. I just went wheeling Sunday and I pulled my buddies 99 wrangler out of a creek, his tires were both half way covered with mud, with my 33"s and my 4.10 gears, so I vote keep the 4.10s.