hey guys, im looking at getting an exhaust for my xj. right now its all stock, its a 93 country with the h.o. and the 5 speed, and 73,000 miles. from what i have seen and heard, i like flowmaster super 44's. I live in Wyoming (no emissions inspection) and im not gonna have a cat on my exhaust system, just muffler. now my question is, should i go with a 2.25 inch exhaust, or 2.5 inch? and while im talking about it, does exhaust on these give any seat-of-the-pants performance? and how much of a difference does it make getting a high flow intake (k&n or such)??? thanks for any info

 

I'd edit this post and take this line out, your gonna have people all up your *** for this comment.

 

Anything larger than 2.5" and your going to loose your mid range torque.
Without a cat, I would think that 2.25 would be good.
Check the Jeep Speed Racer project and see what they used.
http://www.jpmagazine.com/projectbui...eed/index.html

 

you need to read the stickys and take the comment out of your post, and you might get answers. i would go with the 2.25. And a true cold air intake will give you added performance, not just a tube and filter but the cold air sheild.

 

I just love sitting in traffic behind a car with no cat. That's just great. You know, a car without a cat puts out as much pollution as like 50 identical cars that have their cats installed. Just put a hi-flow cat on there and be kind to your environment.

 

x2, and I wouldn't go anything over 2.5" on the exhaust. Honestly, I'd do a 2.25" cat and muffler, with a 2.5" outlet on the muffler and 2.5" tailpipe. XJ's like back pressure.

 

The inlet of the stock cat is 2.5" and goes to 2.25" So if you are going for full new exhause, pick up a universal 2.5" cat, muffler of your choice (I prefer Magnaflow/bullet performance and aero turbine) and turn down or pipe as far back as you want to go.

 

A little myth busting.........

http://www.jpmagazine.com/techarticl...ies/index.html

 

Id rather smell unburnt hydrocarbons than post cat exhaust, it smells nasty. BUT, I have a cat on my jeep and plan on keeping it that way.
OP, keep your cat or get a high flow.

 

You guys are all enviromental? Yet off-road and cause errosion, and stroke out your engines.
No emissions so no worries of a cat. A LOT of people go with ot. Tractors go without it, lawn equipment go without it.
I used to have a 240z and not even federal law required me to have a cat. Get over it. Diesels are on the road, so WTF. No one will reply if you don't have a cat?

Even in areas that have emissions, people will put their cat exhaust just for emissions or put a fake one on.

Get over it. Sry, but seriously. And hypocritical.

I'd go 2.25 myself. Even on a stroker and without a cat. I'd go catless in a heart beat but I live in an emissions county. And yes, I do recycle. Seriously.


Oh, btw, it isnt like running without a cat is like having the exhaust of 50 cars. It is more like 3 to 5 tops. My friend has an Eclipse without a cat and somehow passed emissions testing. He has a 3.0L v6 200hp SOHC, and I have a 2.8L v6 125hp OHV. His emissions were only 4 times worse than mine, but was still within legal limits so passed caused they thought he had a cat.
If the exhaust came out of 50 cars, this guy would have been WAY over legal emission limits without a cat.

 

you say you hate being behind a vehicle without a cat: what about a diesel that blows so much black smoke through an intersection that you cant see? or putting a lift and 35 inch tires on a cherokee? mine is stock and i get 22-25 miles per gallon, what would it get after a 4 inch lift and 35's? it wouldn't improve, that's for sure. im not saying that lifts are bad and not to do them, i plan on one, all im saying is that before people start preaching to me about being environmentally friendly, get some perspective. so you have a cat on your jeep that gets 12-14 miles per gallon, and i don't have one on mine that gets 22-25 mpg....anyway, completely off subject. I figured on the 2.25 inch anyway, and after the responses, i think that's what ill go for. thanks for all your info

 

AMEN BROTHER

 

Alright, you don't care about your environment. That's fine. How about this, you care about performance right??...Well, the Jeep 4.0l inline six is a torque monster. We all know that. But it requires a certain amount of back pressure from the exhaust system to maintain that awesome amount of torque. If you remove the cat, you will be removing a percentage of this back pressure and therefore will be robbing yourself of some mid range torque. So....Maybe you should think about installing a hi-flow CAT to actually improve performance and as a bi-product you can just happen to be kinder to your environment. :P

 

im confused about the whole back pressure thing? I had my entire exhaust off except the headers bacause i was in the process of editing some things, and drove it like that for a week. It road great. not better not worse just the same. Even when you hit or let off the gas quickly the trans never jerked from loss of pressure. i dont think our jeeps need back pressure. i believe its just a giant scam to get people to spend money on these expensive perfomance parts. Think about it. How can a cat be high flow but not loose this supposible needed pressure? its not scientifically possible unless they had a check valve in them. I have put 35000(158000 on odom) miles on my cherokee with my nonbackpressure exhaust and its as strong as ever.