Best Performance Exhaust?

10910 Views 47 Replies 19 Participants Last post by tank, Feb 28, 2008

Xyster

Discussion Starter · Dec 1, 2007

Any suggestions?

1 - 20 of 48 Posts

WTF_LOL

· #2 · Dec 1, 2007 (Edited)

Since you have a 4dr I would really look at relocating the muffler.

Here is an example of what I am talking about (not necessarily this particular kit, this is just an example of the relocation)...

http://www.cooltechllc.com/servlet/Detail?no=15

Need a little more info to really answer your question though, what exactly are you looking for?
Ok with louder then stock?
Are you adding headers?
Are you leaving the engine stock?
Are you looking for top performance regardles of sound?
Do you want to keep the cats?
etc,etc,..

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dougnpj

· #3 · Dec 1, 2007

WTF_LOL said:
Since you have a 4dr I would really look at relocating the muffler.

Need a little more info to really answer your question though, what exactly are you looking for?
Ok with louder then stock?
Are you adding headers?
Are you leaving the engine stock?
Are you looking for top performance regardles of sound?
Do you want to keep the cats?
etc,etc,..

I have to agree. I went with a cat back “Dyno max” before I joined this forum and put a smaller muffler in the factory location then saw a different one that left that area open. Hind sight is 20-20. I will have to say I also put on the air raid CAI and between the 2 in can feel a difference and see the difference at the gas pump. Not a whole lot but every little bit helps.

Can you delete the cats? I was told that the oxygen sensor would notice and make the engine run like crap…

venom

· #4 · Dec 1, 2007

if you do a cat-delete, the computer will be very unhappy with you and punish you severely.
A simple hi-flow cat would be the way to go.
Unless one of the tuner makers (Diablo, Superchips, etc) comes out with a programmer that lets us turn off the O2 sensors and so on (like I had for my supercharged ford truck) then you could do whatever you want.
Hi flows still scrub the gases but without much backpressure though, so they would be my first suggestion.
something like this..
http://www.troyerperformance.com/cgi-bin/ppistore.pl?user_action=detail&catalogno=94306

Xyster

Discussion Starter · #5 · Dec 1, 2007

I'm looking at doing cat-back, & the main reason is for additional hp, although any mpg savings is always welcome, it's not that big a deal. I had my eye on the gibson split, but I haven't gotten any feedback on that one yet. And I love that airaid cai, it definitley made a difference just by itself. As for the headers-not at this time, maybe down the road.

venom

· #6 · Dec 1, 2007 (Edited)

for what it's worth, I remember reading one review of the gibson split on another site - don't remember which one, but the guy was NOT happy with it, he said it was actually quieter than stock and seemed to make no difference in performance at all.
I just made a mental note to cross that one off my list, so I don't remember what site, the specifics, etc.
Maybe someone on here actually has it and can comment more.

RubyMtnRubicon

· #7 · Dec 1, 2007

Duel exhaust on lower compression engines usually give no power gains and in some cases reduce power. But with the 3.8 being 9.6:1 compression your probably not going to lose any power and probably not going to gain much either.

Gibson also states: Not recommended for towing, because carbon monoxide may be drawn into the interior rear of a vehicle when an exhaust pipe directly exits to the rear of the vehicle.

dodge8604

· #8 · Dec 1, 2007

I had this relocation idea the moment I bought my JK and looked underneath it. UGLY! NASTY! Whats up w/ that huge muffler? And that huge space in the mid-section is not being used very wisely!

Honestly, this kit could cost any of us the price of the muffler itself plus or minus maybe a tailpipe extension. You can use ALL of the stock piping with this too. Although you may want to switch to the hi flow cat like Venom said, this mod is very simple and you need about 3-5 tools and a socket set(maybe)

--A Sawz-ALL
--Welder of your preference i guess, unless you're gonna clamp it
--Drill
--Sockets
--New muffler w/ in and out to Jeep Specs

All I was thinking of doing was cutting everything from the Cat Back out. Move the stock heat shield by marking and drilling holes in the cab floor, using the stock holes w/ the stock heat shield (instead of buying one or fabing your own) to the spot that you will be placing the new muffler(BTW that HUGE heat shield may help some of the drone in the cab if your muffler is smaller than the stock muffler which it should be LOL). Put on ur new cat or keep on the stock one and cut the stock pipe to length to fit your new muffler under the new heat shield location. weld em up and then use the remaining pipe (should have all the correct bends in them) to bring the exhaust back to AT LEAST over the axle. Now I was thinking of leaving the exhaust pipe cut here to reduce the chance of pinching it off while ur on the trail...

But the fumes may come into the cab, so I may just bring it all the way back on the left side, dunno for sure yet...I guess its up to the owner.

Now I devised this from just a glance under my JK I havent done any measuring at all yet, so corret me if I'm off on something, but I think this is a great idea to correct a flaw in the new 4 door JK design.

This is definitely a mod I will be doing shortly after I find a good muffler. And its DEFINITELY alot cheaper than most Cat-back kits!

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WTF_LOL

· #9 · Dec 2, 2007 (Edited)

2

venom said:
if you do a cat-delete, the computer will be very unhappy with you and punish you severely.
A simple hi-flow cat would be the way to go.
Unless one of the tuner makers (Diablo, Superchips, etc) comes out with a programmer that lets us turn off the O2 sensors and so on (like I had for my supercharged ford truck) then you could do whatever you want.
Hi flows still scrub the gases but without much backpressure though, so they would be my first suggestion.
something like this..
http://www.troyerperformance.com/cgi-bin/ppistore.pl?user_action=detail&catalogno=94306

No need for all that. There is an old school mechanical fix that I am surprised not many people know. You just use a $5 spark plug non fouler. just put the non fouler between the rear o2 and the bung and presto, no CEL. The thing with the JK is there would be a lot of piping to replace if removing the cats, which is oppurtunity for better flow but, unless you are running a turbo or SC I just don't see it being worth the $$. Shouldin't affect scavenging in such a negative way as the Cats are far forward, where the gasses are still warm. Heat wrap back to where the pipes meet and veloscity should stay high making up for the difference. On top of the small benifit, you would then have to deal with the vapors. This is the first vehicle I will be leaving the cats on in quite some time. While I am used to that "burnt cookie" kind of scent, I can only imagine it in a SWB topless vehilce driving 2 mph :smokin:

:smokin:

(Sometimes you made need two)

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dodge8604

· #10 · Dec 2, 2007

WTF_LOL said:
No need for all that. There is an old school mechanical fix that I am surprised not many people know. You just use a $5 spark plug non fouler. just put the non fouler between the rear o2 and the bung and presto, no CEL. The thing with the JK is there would be a lot of piping to replace if removing the cats, which is oppurtunity for better flow but, unless you are running a turbo or SC I just don't see it being worth the $$. Shouldin't affect scavenging in such a negative way as the Cats are far forward, where the gasses are still warm. Heat wrap back to where the pipes meet and veloscity should stay high making up for the difference. On top of the small benifit, you would then have to deal with the vapors. This is the first vehicle I will be leaving the cats on in quite some time. While I am used to that "burnt cookie" kind of scent, I can only imagine it in a SWB topless vehilce driving 2 mph

so you're saying to leave the stock cats on, cut them off completely or to get the hi flow cats? Also, I dont understand how he'd be getting fumes if they welded up some new piping? I'm a noob so lower your nomenclature to my level when you explain all this to me LOL :grinpimp:

:grinpimp:

WTF_LOL

· #11 · Dec 2, 2007 (Edited)

Leave the cats (unless you are running a turbo or SC). Would not be worth replacing for a handful of reasons

Hi flow cats in my opinoion would not be worth the $$$. Wouldn't be more then a couple HP and probabably all in the top end at that.

The fumes are pretty strong with no cat, even with the tail pipe in a good location, with no top, offroad speeds, you will get dizzy, lol :jeep1:

The smell would not be coming from where the cat attaches, it would come out the tail pipe..

Xyster

Discussion Starter · #12 · Dec 2, 2007

Thanks for the feedback on the gibson, you just saved me some $. Any feelings on banks monster?

RubyMtnRubicon

· #13 · Dec 2, 2007

Save your money on any bolt on system, just go to a reputable exhaust shop and have them bend some tube and weld on a Magnaflow or whatever muffler you like. Doing it that way will save you a few hundred dollars for other mods. Who cares if its polished stainless. Nobody is going to see it unless you flop over and at that point you have issues other then some people not seeing some shiny tubing.

Xyster

Discussion Starter · #14 · Dec 2, 2007

Good point on the stainless. But I'm not sure how I'd save $ based on your comment. What other mods are you referring to? Also, a bolt on I can do myself, saving on the labor, as where I don't have the welding equip or skills needed for non-bolt on. The Magnaflow goes for 600 plus, and then theres the labor, as where a banks or equiv. goes for around 400-500 with no labor.

venom

· #15 · Dec 2, 2007 (Edited)

As far as I'm concerned, the only bolt on kit I would even CONSIDER would be from cooltech. They're the only ones that relocate the muffler under the Jeep where it ought to be. Plus they gouge the least for the kit at $321 shipped. Also I hear nothing but great things about their customer service.

What would be awesome would be for someone who has a buddy in the exhaust biz to get us some tailpipes made up and sell them.
Drop your stock muffler, bolt on a new tailpipe and cut in the muffler of your choice upstream under then Jeep where it belongs and there you have a killer exhaust system for cheap!

RubyMtnRubicon

· #16 · Dec 2, 2007

Xyster said:
Good point on the stainless. But I'm not sure how I'd save $ based on your comment. What other mods are you referring to? Also, a bolt on I can do myself, saving on the labor, as where I don't have the welding equip or skills needed for non-bolt on. The Magnaflow goes for 600 plus, and then theres the labor, as where a banks or equiv. goes for around 400-500 with no labor.

Huh? A muffler will cost you $150 at the most. Having a good exhaust shop bend you some pipe should be close to another $150 at the most, labor is cheap. So figure $400 (should be less though), that saves you $200 + labor over the Magnaflow cat back system. At the very least its going to save you time (time is money right?) and a few busted knuckles.

RubyMtnRubicon

· #17 · Dec 2, 2007 (Edited)

venom said:
As far as I'm concerned, the only bolt on kit I would even CONSIDER would be from cooltech. They're the only ones that relocate the muffler under the Jeep where it ought to be. Plus they gouge the least for the kit at $321 shipped. Also I hear nothing but great things about their customer service.

What would be awesome would be for someone who has a buddy in the exhaust biz to get us some tailpipes made up and sell them.
Drop your stock muffler, bolt on a new tailpipe and cut in the muffler of your choice upstream under then Jeep where it belongs and there you have a killer exhaust system for cheap!

I wish there was a place to relocate the muffler on the 2 door. :bawling:

And yes their customer service is great. I received a broken cb antenna with their kit, they sent me a new one no questions asked.

dodge8604

· #18 · Dec 3, 2007

You shouldn't need ANY extra pipe to be bent at all if you do what I said...the easy way would be to cut the length of the muffler out from the pipe that runs down the left side, clamp in the muffler, and then cut off right in front of the huge stock muffler and run a foot or so turn down tip out the back (mind you like $20 at most from any auto parts store) Also dont forget to relocate the stock heatsheild too.

EASY, SAWZALL AND SOCKETS THATS IT!!

you are lookin at less than $150 bucks with a pretty good muffler.

Flowmaster 40 series - $70

Piping and clamps - $30 +/-

grayghost

· #19 · Dec 4, 2007

Gibson Exhaust??

I have a Gibson exhaust with KN air filter NO noticable power increase. Won't buy again.

Xyster

Discussion Starter · #20 · Dec 4, 2007

Thanks for the tip, that's a shame about the gibson-do you think it's the make & model of the exhaust, or do you think all bolt-on's are likely to be this way?

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