Big D2

Keep it legal...ya right...check out our fellows location...Kuwait City....where oil is cheaper than water. I think the last thing he's concerned about is a little extra emmissions.

So since you're being legal, lol, that is a lot of work. But like a few said the last thing you want to do is loose prescious low end torque. I would do a cat back exhaust, intake and a programmer like Hypertech. I like that chip cause it improves torque at low rpms.

RedneckJeep

Well, look at your statement. CAT BACK. Can't be a cat back system without cats, can it? ....and that Hypertech unit? Guess what, it's DESIGNED and PROGRAMMED for use on a STOCK, LEGAL engine.

Blue

If fuel is that cheap and plentiful in Kuwait, why the hell worry about it in the first place.

JK-Q8

whos worrying about the fuel?, i fill my jk with $15, so no the fuel is not an issue. I have currently the gibson dual, and so i should get a k&n filter for example and a programmer?
I don't know whats the programer?
and how it works?
if my warranty will still be good with it?
how to use?
how much does it cost?
any side effects with the programer?
will that give me a bit more sound?
sorry about so many questions but am a newbie in these things.

Cruiser

You will not see much difference in a high flow cat,, and you will lose low end power when they are removed.. High flow cats do exist and do have better flow,, but with the modern cats its not significant enought to bother.. The muffler is the biggest restriction in your system.. If you want go buy a backpressure test kit from snap-on and do the test.. I've done it before on several cars.. Unless your running major mods you cant benifit from lower backpressure that removing the cats will provide.. This will also screw with your programing,, it will take it out of its set parameters.. Oh,, one more thing,, backpressure has zero to do with heat of your cat.. that is a side effect of the reburn or burning of the lefover hydrocarbons in your exhaust.. not the pressure.. The cats are mosty raduim and platnium and are slightly radioactive, when the hot gases pas thru the honeycomb material there is a chemical reaction and the HC traces in the exhaust burn up thus cleaning your exhaust.. On the older cars the cats were filled with a bed of beads of the same material and created an incredible amount of backpressure.. When they came out with the honeycomb they dubbed them "high flow" The Hi-po ones have more of an opening or passageway reducing the backpressure,, and they clog less,, but at the cost of efficiency and polution and price, for little or no HP gains.. If your looking for fastest et on a 1/4 mile track then you would be doin this type of mod.. But for torque and grunt for a 4wd the 3.8 needs the low end you would loose with this.. A CIA and a better flow exhaust would give you enough without loosing much low end..
Sorry its long.. been home staring at this screen for 4 weeks now..
anothe 5months to go back to work..

Warlord2

[QUOTE=Cruiser;436222] The muffler is the biggest restriction in your system..QUOTE]

I would have to dissagree with that, coming from a turboed wrx sti. Its a known problem that the cat is the most restrictive of anything on the exhaust. Ive seen dynoed graphs with cats on, with high flow cats on and no cats on. VERY evident when you take the cat off there is a huge decrease in flow restriction. My sti had 3" mid pipe and goes all the way up to 4" at the rear. I left BOTH cats off and had to mess with the BOV just to not over boost my car. I wouldnt take the stock cats off of a jeep though. Really no point in doing it unless just messing around or taking it to the dyno/track. Now if you had a SC or turbo on it, might be a little fun to see what difference it makes because its just a whole different ball park then.

Big D2

Hypertech does have a setting for modified engines...no?

JK-Q8

Okay so from what i understand. since its stock leave the cats on. I put on the gibson dual. I didn't feel change in the power, but all people say i lost low end torque, so to get back up i need a air filter? and a programmer? What does the programmer do? will it void warranty? any side effects? will i feel i great difference? how much do they cost?

Cruiser

I'll correct myself here,, with a normally aspirated motor the most restrictive is not the cat.. once you have a turbo or supercharger the flow of exhaust steps up considerably.. Tested this on a t-bird with a turbo and on a f-150 lightning supercharged.. On those when boost came up the cat became the problem.. With a 3.8 normally aspirated engine and the newer style cats that are used today it should not be an issue.. If you put a supercharger on,, all bets are off..


You wont feel much with the exhaust till the intake is changed.. and it goes the other way to.. The programer,, not sure on warr.. try the cia first and drive it hard to let the computer learn your driving style..

RedneckJeep

Not trying to insult....but it seems you're just throwing parts at your Jeep in a haphazzard fashion. You need to do some research. I mean, if you want it to just sound cool, that's one thing. If you want it to actually respond, that's another. It just looks to me like you're going to end up spending a lot of money and wishing you had left it stock in the end.