My 88 with a 2.5/AX5 is only a 2wd, and let me tell you, it PULLS! It don't matter if it's from a dead stop, or cruising on the interstate, all I have to do is half to three quarter throttle, and she's gone. I had taken her down to a meet and greet a while ago (when I lowered her), and on our way back, Geonovast, Jeepco, and I were playing pass the leader on the interstate. I kept her in 5th gear the whole time, and never had any troubles passing them up. They could have swore I dropped a gear to get by them as fast as I did, but I never once dropped a gear once I got to speed. This is on a 160k mile motor that has seen a LOT of abuse from me in the past, so I wouldn't discredit the 2.5s very much.
Okay, Maybe the 2.5 that my 85 xj had was just a bad apple. Which it had seen better days though. It probely didn`t help it either that it is carbed & the compression sucked. Thats probely why it didn`t have any power. It sounds like the injected 2.5`s are a lot better.