My jeep is a 1999 bone stock 4.0L. In a couple months I am putting a 4.5 Rough Country suspension life. I was told though that a chip would help me on horsepower. Someone else said I should invest in new headers. Not sure which way to go. Give me some ideas on how to gain more horsepower and your opinion on the best way to go lifting it.

 

Stay away from a chip, they do not work well on these engines.

Your best bang for the buck is, intake and exhaust. If you have not done a tune-up then that would help as well. You can also change over all the fluids to syn to get some free power out of the drive train. Even running an electric fan in place of the mech fan will decrease the drag loss and increase power.

Give the forum a search, I know there is other threads about this that might have some good info.