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Discussion Starter · #1 ·
This may have been discussed in other threads but does the JBA Evol Cat-Back replace the resonators? I have a KC 4X2 and while I was underneath it today I noticed the piping around the resonators looks real restrictive. If the JBA Cat-Back doesn't replace the resonators with straight pipe or something then I don't see much performance gain since the restriction at the resonators seems extreme.
 

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TitanHauler said:
This may have been discussed in other threads but does the JBA Evol Cat-Back replace the resonators? I have a KC 4X2 and while I was underneath it today I noticed the piping around the resonators looks real restrictive. If the JBA Cat-Back doesn't replace the resonators with straight pipe or something then I don't see much performance gain since the restriction at the resonators seems extreme.
Here's what little I know. The JBA Evol kit that is up for raffle is a cat-back for a 4x4 and a reso-back for a 4x2. In other words, it will not replace your resos. Back in the early day, JBA only made one exhaust for the Titan and it was modeled off a 4x2, so it was a cat-back that replaced everything from the cats back including the pipes with the O2 sensors and resos. This created a problem on the 4x4's since they have 4 cats and no resos. A couple months ago, they re-did their exhaust kit so that it is 4x4 friendly and is a cat-back for them and is a reso-back for the 4x2. I have no idea if they still offer a true cat-back for use 4x2 guys.
 

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Discussion Starter · #3 ·
HavockWK said:
TitanHauler said:
This may have been discussed in other threads but does the JBA Evol Cat-Back replace the resonators? I have a KC 4X2 and while I was underneath it today I noticed the piping around the resonators looks real restrictive. If the JBA Cat-Back doesn't replace the resonators with straight pipe or something then I don't see much performance gain since the restriction at the resonators seems extreme.
Here's what little I know. The JBA Evol kit that is up for raffle is a cat-back for a 4x4 and a reso-back for a 4x2. In other words, it will not replace your resos. Back in the early day, JBA only made one exhaust for the Titan and it was modeled off a 4x2, so it was a cat-back that replaced everything from the cats back including the pipes with the O2 sensors and resos. This created a problem on the 4x4's since they have 4 cats and no resos. A couple months ago, they re-did their exhaust kit so that it is 4x4 friendly and is a cat-back for them and is a reso-back for the 4x2. I have no idea if they still offer a true cat-back for use 4x2 guys.
Well that sucks! I wonder why they didn't just make a Cat-Back for the 4X4's and leave well enough alone on the 4X2's. I'm sure you've looked under your truck and the piping going in and out of the resonators is tiny. So if the JBA is only resonators back on the 4X2, it will do little in my opinion in the way of performance since bigger pipe after a huge restriction is useless. Oh well . . .
 

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TitanHauler said:
HavockWK said:
TitanHauler said:
This may have been discussed in other threads but does the JBA Evol Cat-Back replace the resonators? I have a KC 4X2 and while I was underneath it today I noticed the piping around the resonators looks real restrictive. If the JBA Cat-Back doesn't replace the resonators with straight pipe or something then I don't see much performance gain since the restriction at the resonators seems extreme.
Here's what little I know. The JBA Evol kit that is up for raffle is a cat-back for a 4x4 and a reso-back for a 4x2. In other words, it will not replace your resos. Back in the early day, JBA only made one exhaust for the Titan and it was modeled off a 4x2, so it was a cat-back that replaced everything from the cats back including the pipes with the O2 sensors and resos. This created a problem on the 4x4's since they have 4 cats and no resos. A couple months ago, they re-did their exhaust kit so that it is 4x4 friendly and is a cat-back for them and is a reso-back for the 4x2. I have no idea if they still offer a true cat-back for use 4x2 guys.
Well that sucks! I wonder why they didn't just make a Cat-Back for the 4X4's and leave well enough alone on the 4X2's. I'm sure you've looked under your truck and the piping going in and out of the resonators is tiny. So if the JBA is only resonators back on the 4X2, it will do little in my opinion in the way of performance since bigger pipe after a huge restriction is useless. Oh well . . .
There have been a few guys that have removed those resonator pipes and taken them to an exhaust shop and had a pipe made up to replace it. That would be the way to go if your concerned about the restriction. You should be able to get that done pretty cheap.
 

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QWIKWHIP said:
There have been a few guys that have removed those resonator pipes and taken them to an exhaust shop and had a pipe made up to replace it. That would be the way to go if your concerned about the restriction. You should be able to get that done pretty cheap.
That's what I was going to suggest. I've got the 4X4, so I have no reso's. Let us know what you do, okay?
 

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Since I do have a 4X2 would it make that much of a difference to have them replaced? Whatcha thinking that might cost..... I've never been under mine yet so I don't even know what it looks like yet.
 

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Your gonna give bill a big head with your signature!! :lol:
 

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LOL I still crack up everytime I see that avatar of yours.
m4ck
 

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Rossi said:
Since I do have a 4X2 would it make that much of a difference to have them replaced? Whatcha thinking that might cost..... I've never been under mine yet so I don't even know what it looks like yet.
The pipe to fore and aft the resos is about 2" I think. The inlet and outlet for the reso are about 1.5" for about .5".

If you check out the head's posts about his exhaust performance upgrades (not sure if he posted the info here or just on TT), he got the biggest performance boost when he replaced the OEM resos with some Moroso resos and bigger pipes (2.5" I believe).
 

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That does make a big difference replacing the resonators. I did it on my last truck and kept the pipes when I traded it in for the truck I have now. Mine are 2.5" straight pipes and you sure can FEEL the difference all through the RPM band. It's a great mod to do whether you have resonators or cats.
 

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hhhmmm...living in the great state of California I wonder if you are even permitted to remove them. Probably would have to ask a shop that's up on all our quirky smog laws here.
 

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Re:

Rossi said:
hhhmmm...living in the great state of California I wonder if you are even permitted to remove them. Probably would have to ask a shop that's up on all our quirky smog laws here.
I think you can, I did it on my former F-150 4X4. As long as you still have cats on it. I took it to Ledezma Muffler Shop in Chula Vista, California last year..... :)
 

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Not sure, but I don't think removing the cats is "50 state smog legal".

Also, might affect your warranty. Scarab on TT tried to ask his service manager about this, but never got a straight answer. He got one of the early model JBA kits on his 4x4 and didn't realize until after that he had 4 cats and no resos.
 

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Discussion Starter · #16 ·
Slurppie said:
Looks like I ordered mine just in time. (Yes this is a totally meaningless post).
You scored and got the original system that replaces the resonators right? You lucky dog. :) Your post wasn't totally meaningless unless you think gloating is meaningless. :) :) :) :)
 

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Discussion Starter · #17 ·
Rossi said:
hhhmmm...living in the great state of California I wonder if you are even permitted to remove them. Probably would have to ask a shop that's up on all our quirky smog laws here.
Removing the resonators should be no problem for us Californian's it's the cats you better not touch.
 

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I would just have to beleive that if you did some beating of these people that you could probably find an old system. hhhmmmm....thinking here....I'll send them a message and see if I can get a response...first I have to find an e-mail address.
 
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TitanHauler said:
Slurppie said:
Looks like I ordered mine just in time. (Yes this is a totally meaningless post).
You scored and got the original system that replaces the resonators right? You lucky dog. :) Your post wasn't totally meaningless unless you think gloating is meaningless. :) :) :) :)
Just looked, gloating isn't in my dictionary :wink:
 

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Discussion Starter · #20 ·
Ok, after hearing a bunch of conflicting information I made a call to JBA today to try and get the real scoop and here is what the tech told me. The current kit being produced (Post 12/04) is for the 4X2 only. It DOES replace the resonators but won't work on a 4X4 because of the extra 2 cats. They will have a 4X4 specific kit coming out soon but it is currently still in development. He said all kits manufactured before 12/04 will work on both 4X2 and 4X4 but will only be truly "Cat-Back" on a 4X4 and "Reso-Back" on a 4X2.

Anyone heard anything different from JBA directly?
 
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