I have a 2000 TJ with the ever so weak 2.5L 4 cyl. i was wondering what some cheap upgrades would be to free up some horsepower, which brands and things like that thanks for the help  

your trying to polish a (peformance) turd. Bolt-ons in general tend to be a huge waste of money, you can spend thousands and bump up your power 10%. 10% of your 120 is 12. not a good hp/dollar investment. if your dead set on trying give the hamsters steroids, I'd suggest opening up the stock airbox and using a 4.0 throttle-body. fancy ignition don't do squat to a modern engine (I learned that the expensive way). open element filters suck hot air, when they aren't getting sprayed with mud. I rarley hear people saying good things about the chips, and most require premium. MAP adjusters/ thermostats, just richen up the mix, not realy the best way to go.

I cant realy speak on the exhaust side, but make sure you upgrade the most restrictive elements, not something that looks cool, or is easy to change.

about the only relativle cheap thing you can do that you will actualy feel is NOX, but then you always buying bottles. and to do it "right" isn't realy all that cheap either.

If you want a race car, open up your wallet and do an engin, trans and transfer case swap. If you want a trail rig change the axel gearing and put a 4 to 1 low gear in the transfer case. You could also add a Klune-V under drive. If you are street driving the thing most of the time leave it alone and save gas money.   

i turn 36's on a 2.5L, 5.38 gears.... gearing is the solution, don't waste money on hp upgrades....  

I put a Rusty's offroad throttle body spacer, air tube, and cat back with a flowmaster on my 00 TJ with a 2.5. it has 33's with 3.73's. not much of a notice in power but am getting close to 40 miles more to a tank of gas. I have 4.56's to put in now when i find the time. almost wish i would have bought the gears first.  

I have a short body Cherokee with the 2.5. I did the rustys K&N upgrade and a Dynomax CatBack exhuast. It set me back about $150 +-, was simple and made a noticeable improvement in the pick up and milage.  If you do this pick up a ricipracating saw to remove the old pipes, had I dun that it would have cut the install time by 50% and the cussing by 75%.