So it looks like 33's are not the best idea, I think that im going to stick with my 31's and just go wider. as far as the engine mods that bounty hunter suggested "Consider an electric fan to replace the mechanical, a cold-air intake system, and a 62mm throttle body." what kind of performance should I expect, and I was going to buy a safari snorkel so would that act as a cold-air?
I have done all these mods that you mention, and I am installing a safari snorkel (which WILL act as both a cold air intake and even a bit as a ram air if you face the scoop forward). From the mods, dont expect huge "feel-of-your-pants" differences, but you will notice that you will not need to downshift as often as you used to (I also run 31's, and did all the mods before regearing to 4.88's, which came about a year after all the other mods were installed). The biggest difference for me came from the regearing, though, but that was also the most expensive mod.
The fan will free up some ponies, and I recommend the Delta Current Control FK35 controller if you decide to go with the FoMoCo fan (which has worked beautifully for me). With the 62mm TB, what you are looking for is more air coming in to the engine, but in order to get the most out of the air, you will need the right amount of fuel available, and for you, this can be had with another junkyard swap, this time, by means of the Ford mustang injectors. Another thing to consider is the air filter; I used to run the K&N filter in the stock box, but now changed to the FRAM AirHog.
Once you got all the air and fuel going in, you need to consider how to light the mixture; I recommend a Performance Distributor kit (it includes the screaming Demon coil, Live Wires, cap and rotor) and match it to .065 gapped plugs which will give you better ignition.
After the combustion, you need to think on how to get all these gases out, and this is where a high flow cat and cat back system help (and headers if you want, but just make sure they increase low end torque, and not horse power at the higher rpm's, as this is useless for us Jeepers).
Again, I reinstate that none of these mods will make HUGE improvements, but all together, they do add (or free up) some ponies. But it will not be like regearing. If you want some ideas on how to build up the 2.5L, i recommend you visit
www.4bangerjp.com as you will find TONS of information there (rebuilding of the 2.5L for higher compression, turboing the 2.5L, supercharging the 2.5L, etc). There you will find some 2.5L that will give the 4.0L a run for its money (by the way, both Bounty and I are also in the other forum, and we both have 2.5L Jeeps).
Felipe
