I've been beating on my 4 door JK for over 4 years on level 4 and 5 trails. I've had good luck with not breaking parts. Broke a couple of rear stock shafts. Ran stock drive train up to 37"s and upgraded the shafts and 5:38 gears when I went to 40"s. I've broken one time when it was not drivable back home and I was acting a fool bouncing it 4-5 feet off the ground just for fun on Vertical Challenger. Gas milage is around 13 mpg at this point. The power sucks unless you swap in a Hemi but they will take some serious abuse for an off the shelf Jeep. :****: