Great. Another dude is asking the internet how to get more power from is 4L. Well, not entirely. And by that I mean, I've done some research, and there are reviews that come from both sides of the fence. What I've noticed is the ones who do a bolt on mod are disappointed bit the ones who do a complete engine mod, and spend a big chunk of change do get some excellent gains. Bit the consensus is, there's no middle ground. You can't just do the cat back exhaust and be happy with the money you spent. And you can't just get a cold air intake.

But, I've read if you let the whole motor breathe better with a completely new exhaust, intake, cam, heads, and then let it drink right with some high flow injectors, you get a whole new animal. But, why stop there? Why not make it a stroker and add in some high compression rings and pistons? Well, yes, that's all internal, costs a lot of money, takes a lot of time, and in the end you have a monster 4 litre inline six. So, congratulations on your newfound bragging rights. But, was it worth it?

Toyota makes a much smaller inline six, the 2JZ Supra motor. It's only a 3.0 but everybody in the tuner scene wants one so they can mess with it and get 2000 horsepower. Has anyone seen an AMC 4.0 get 4 digit power numbers? I haven't.

My point is, leave it alone, or put about 5 grand into makin the motor kinda cool and have a jeep witha loud and powerful tractor motor?

In my particular case, I have an '89 EFI model, which has good injectors from stock but the heads are reportedly the worst, and a next gen 91-96 would trump all. The only reason I've considered upgrading is because the rear freeze plug has popped out and to replace it, the intake and exhaust manifolds need to come off. Upgrade while it's apart, or clean it and put it back on?

Tell me what you've done, decided not to do, why, and how you can prove any gains or losses.