I do believe they are made to rev higher than sixes. I also have very little experience with the 2.5 L Jeep engine. The only 4yl I've ridden in recently is a 4 speed but 4th gear is 1:1 in a 4 or a 5 speed, over revving in 4th is impossible in my buddy's Jeep! <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />