Has anyone ever done this? Can you tell a difference in power? Also anyone ran dual exhaust? Do either of these actually increase the power to where you can notice some?

 

A cold air intake and just going to a single exhaust with 2.25 or 2.5 tubing helps the 4.0 motor breathe much better. You will notice a difference when you push the "Go" pedal. Before I put the lift and 33 inch tires on I was getting 20-22 mpg. I still get 18-19 on the highway even with 4.56 gears and front and rear lockers.

 

i got a cold air intake on mine and a 2.25 " flowmaster 44 muffler cat back system and you can tell a difference and i get alittle better gas milage too with it

 

ya there is definitely going to be a difference, but you ought to replace the headers back with it so its a noticeable change.

 

What do you mean Headers Back?

 

the headers are the beginning of the exhaust. there are 6 tubes that connect to the engine and all converge into one tube it looks like an octapus kinda below some stuff on drivers side compartment. then from the headers it goes to the catylitic converter and then to the muffler and then out to tail pipe

 

Headers

 

Anyone got any pics? Sorry kind of confused.

This will be my daily driver so I am looking for the best MPG I can get. I will be driving 235/75/15 and no lift for now. So I am wanting to see if I can stay above 20 mpg since 90% of my driving is highway. I will be replacing fuel filter, putting a cold air intake on. And my Jeep currently has no muffler/cat so I should get a flowmaster for decent MPG. Anything else I missed?

 

So replace the header or the gasket? I guess when he said Back it threw me off haha.

 

A cold air intake along with all the basic mods will definitely improve performance.

 

if youre stock you should hit 20-21 easy one main thing thats easy is constantly check tire pressure for mpgs. how much are you looking to spend on the intake? I built my own cold air intake, really easy. I just tied it into my stock air box so that the K&N air filter is housed in there and draws air from behind drivers headlight. this give the advantage of cold air. alot of "cold" air intakes are just open in the eng compt drawing hot air. the whole comcept is to have cold air so you get more dense consentration of O2 molecules feeding to the engine. so if you get a really good heat shield it will help alot and there are fab forums on here about that. also having it in the air box keeps it way cleaner from mud and water up in there. do you have any fab skills or interest? there would be no work with metal, only plastic and easy stuff

 

sorry man. I meant get a good set of headers, and just make your own better flowing exhaust system. Your engine is basically a fancy air pump, that uses a explosion to pump the air in and out. the more clean, cool air you get in and the faster you can pump the old used air, the better your gas mileage will be. But don't expect anything over 25 stock.

 

So heres what I did. this was kind of a spur of the moment project I did a while ago. I ordered a kit from ebay for cold air intake for 20$ and it gave me the filter, a 2 1/2" pipe and 2 small hoses for the vents. I had it free in my compartment for a while and it got dirty all the time and just sucked hot air. so then I had the idea to fab it into the air box. take the 2 1/2" tube and cut it to size that you want. I connected mine to the stock carb attachment with works great cuz it gives you your angle. then you are going to have to cut out arround the origonal attachment port on the air box lid. take your time with this. guestimate the angle you are going to need so the k&n will sit in the center and make your fist cuts small so you can trim off small sections till you like it.
the shape of the cut out should start behind the origonal port (cab side) and be an oval pointing to bumper side. make sense? you want it to fit as snug as possible without much gap to it, thats why you do small cuts and take your time.
I still need to finish mine with some kind of synthetic material to make a great seal but I have not done that yet because it works great the way it is and I have just had a bunch of other work to do on the jeep so its put off a little so you can use creativity in this step: I filled in the gaps between the air box lid and pipe making a duct tape seal which works great cuz when the engine compt heats up it gets soft and molds to the pipe. I made the oval into a circular opening just large enough to fit the pipe into at a 90 degree angle and then turn it to fit back on top and you will see it makes a seal so one side is on outside and one side is inside

I really recomend using a thicker rubber sheeting that you could epoxy one piece on inside and one on outside to make that circle opening. thats what Ill do next. my duct tape job has lasted about a year and the tape is starting to degrade so I will do this soon aswell.

here is a key part, to avoid frustration have the carb attachment off to fit K&N filter inside and close the box. its a tight fit and will need a little adjustment the first time to seat it properly. then you attach the hose to carb and tighten up all SS clamps. bam you are in business

 

I have a nasty ghetto fab intake with monster k&n 40series flowmaster no pipe after muffler an bored TB I got more power an lil better gas but not 18mpg more like 13 highway but I need gears an tranny work

 

IDK, is stuffing that big pod filter in the stock air box really that much better than just putting a standard K&N in there?