My dual exhaust idea/ questions...

Gris · **Posted:** Thu Aug 31, 2006 11:44 am

I friend has 2 3" flowmaster 40s that are pratically new and will be free if I choose to use them. I was originally going to just upgrade the muffler to a flowmaster 50, but free 40s can't be passed up.

Ok, here's my plan, but I need advice opinions...

The headers come down both sides of the motor. They then bolt into, using some crazy looking springy flange, into a single pipe that merges into the single 2.5" pipe going to the cat, then the HUGE muffler, then out.

What I plan on doing is removing that merge pipe from the headers to the cat. Then running a pipe from each header to it own cat, then it's own flowmaster 40, then out. The flowmasters are 3" but I was just going to run new mandrel bent 2.5" and expand it right at the muffler to 3".

Will a complete exhaust system for each header allow too much flow? Will it sound like a freaking Honda with 2 flowmaster 40s? Can anyone see any issue with this setup at all?

kickit_in4wheel · **Posted:** Thu Aug 31, 2006 5:56 pm

Not sure about the rest, but you will have to do some creative tube work on the driver's side. The transfer case is kind of in the way, and you fuel lines I believe are running the length of the driver's side, and you do NOT want the exhaust pipe too close to the fuel line.

unixxx · **Posted:** Thu Aug 31, 2006 6:26 pm

Gris, in the end how many cats are you going to have? I think you need three to continue to pass emissions.

***EDIT***

NVM, the 3.7L only has two, my bad

Gris · **Posted:** Thu Aug 31, 2006 6:28 pm

2 cats, but I'm gas, not deisel

streetKJ · **Posted:** Thu Aug 31, 2006 9:01 pm

unixxx wrote:

Gris, in the end how many cats are you going to have? I think you need three to continue to pass emissions.

***EDIT***

NVM, the 3.7L only has two, my bad

The early year gas KJs had 3 cats I think (02 and lower), and from 03 on there are only 2 cats.

Gris · **Posted:** Thu Aug 31, 2006 9:27 pm

mine only has 1 cat. early '02.

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

I think you might gain back some high rpm hp, but you're going to drop some low rpm torque.

kolesy · **Posted:** Thu Aug 31, 2006 10:54 pm

KY Liberty wrote:

I think you might gain back some high rpm hp, but you're going to drop some low rpm torque.

So teach a new guy here, The more back pressure you have the more torque you will gain. The less backpressure you have, the more high rpm horse power you gain, but you lose torque?

Waldn · **Posted:** Fri Sep 01, 2006 1:54 am

streetKJ wrote:

unixxx wrote:

Gris, in the end how many cats are you going to have? I think you need three to continue to pass emissions.

***EDIT***

NVM, the 3.7L only has two, my bad

The early year gas KJs had 3 cats I think (02 and lower), and from 03 on there are only 2 cats.

could swear there are three cats on mine
I thought they all had 3

MikeD0106 · **Posted:** Fri Sep 01, 2006 2:13 am

I think there are 3 cats on all libby's also. 2 smaller ones towards the end of each header and then the bigger one before the muffler.

I also see it as being a PITA to set up. Too much in the way, and do you really have a place on the driver side to make it tucked in and secure? I haven't looked on mine so I have no clue what's there, but then mine is a 2x4 also. As far as the sound goes... I'm afraid that it might sound like a Honda or maybe some new mystical sound with that much flow.

Maybe just take one of the muffler's from your friend and have someone do a custom job to make dual outlet's. Then you can send the other free one my way. :wink:

*I'll pay shipping of course*

Gris · **Posted:** Fri Sep 01, 2006 10:13 am

It might end up going as Mike said. Maybe replace the boat of a muffler with the smaller flowmaster then just split the pipe to come out both sides. I still the the true dual though.

Jeger · **Posted:** Fri Sep 01, 2006 11:33 am

Could you run the dual pipes down one side. And either split them off near the back or just run the both out the one side?

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

This is why I went with the Borla cat back dual outlet. It has the look of a dual exhaust and sounds great. It gives a good performance increase, and it's not open enough to cause a drop in torque at low rpms. It also just bolts right in. I got mine off Ebay for $400 including shipping from a dealership in Florida back in 2002.

DarbyWalters · **Posted:** Tue Sep 05, 2006 2:00 pm

If you do the true duals here are some ideas:

Think about a side exiting exhaust pipes

Put in an "H" pipe...it goes between the duals ahead of the mufflers to even out the sound ect.

You could also run the exhaust to the rear axle and use two turn downs and end it there...like old street cars

***Just don't know if you will gain much in the long run

Gris · **Posted:** Tue Sep 05, 2006 3:45 pm

Darby, With your rear-axle suggestion, you mean just stop short of the back of the vehicle so the exhaust actually exits under the back of the car instead of behind the bumper?

Would I have to worry about exhaust getting in the cab with that setup?

gone_jeepin · **Posted:** Tue Sep 05, 2006 5:37 pm

Darby's ideas sound like the best solutions!! I would go as far back as i could then put turn downs, I wouldn't think it would leak into the cab,

DarbyWalters · **Posted:** Tue Sep 05, 2006 5:45 pm

Gris wrote:

Darby, With your rear-axle suggestion, you mean just stop short of the back of the vehicle so the exhaust actually exits under the back of the car instead of behind the bumper?

Would I have to worry about exhaust getting in the cab with that setup?

Yep...run the "H" pipe to balance the exhaust and do the turn downs just ahead of the rear axle. You should not have a problem with exhaust fumes anymore than at the back with a newer vehicle. Just like sitting in traffic in a congested intersection...you won't really notice any difference...and when moving there should be no problem.

Check with your state on inspection rules...maybe it has to go past the rear doors...who knows?

Gris · **Posted:** Tue Sep 05, 2006 9:08 pm

I want to do this...

but I need a eur bumper because of the damned license plate cutout

If I end up going with a single pipe, I'm doing that on the passenger side.

DarbyWalters · **Posted:** Wed Sep 06, 2006 8:27 am

Gris wrote:

I want to do this...

but I need a eur bumper because of the damned license plate cutout

If I end up going with a single pipe, I'm doing that on the passenger side.

I have talked to those guys (French) a few times...good guys...they know about L.O.S.T....

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

If you get one of those bumpers, couldn't you use the Mopar/Borla dual outlet pretty easily. It looks like that's what they did in those photos. I don't think the setup you're talking about will provide the exhaust velocity that you need. I would use the Mopar/Borla and do some custom headers if JBA can't get theirs CARB approved any time soon. I think you'll want to upgrade your throttle body too.

You've got me thinking about getting one of those bumpers and modifying it now.

My dual exhaust idea/ questions...

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