i have some kind of stroker in mine, i haven;t broken it open to measure it but its not a 4.2. its fun, it spins the tires across the intersection, it tows like nothing is behind it, it is a lot of fun. BUT, for the gas mileage, i would rather have a v8. the best mileage i have ever pulled on this I6 is 15mpg (hwy only). normally, its 10-13 (combined city/hwy). i figure that if i am going to get that kind of mileage, i would rather have the roar of a v8 when i stomp the gas.
I don't feel like working on anything at this time so i sold my yj.