Like Jim said....we need to know what year.
Assuming you have an 86 or older CJ....(I have an 84)...the two mods I did that made the most difference....
1. Fixing all the vacuum leaks.
2. New plug wires with the HEI style dist cap. Or, you can just install the HEI dist.
I built up 2 new engines....I tried cams...head mods.....etc....to be honest....couldn't tell the difference....
Jeeps spend most of their time with the RPM's below 2000....headers and the like are a waste of time and money.
If you really want more power....a swap to a newer engine would be better.
Click on the link in my signature to see my SBC swap.