all muffler and exhaust questions go here!!!!!!
CF Veteran
Joined: Nov 2011
Posts: 2,433
Likes: 6
From: Northern MN
Year: 1990
Model: Cherokee (XJ)
Engine: Renix 4.0
You guys are spending way too much on cats IMO.
http://performance-curve.com/thunderbolt-spincat.aspx
Someone asked about a better sounding cat, better flow equals a rawer, closer to straight pipe sound. This is what I have, and it sounded great before I put my muffler on
http://performance-curve.com/thunder...-metallic.aspx
http://performance-curve.com/thunderbolt-spincat.aspx
Someone asked about a better sounding cat, better flow equals a rawer, closer to straight pipe sound. This is what I have, and it sounded great before I put my muffler on
http://performance-curve.com/thunder...-metallic.aspx
I have a '99 Grand Cherokee 4.0L. I am looking to put on a cat back muffler to relieve back pressure...and to sound better.
I don't want a real aggressive sounding muffler...just rumbly
AND...I am looking for an economical soultion, as well.
Any help would be greatly appreciated.
Thanks
I don't want a real aggressive sounding muffler...just rumbly

AND...I am looking for an economical soultion, as well.
Any help would be greatly appreciated.
Thanks
I have a '99 Grand Cherokee 4.0L.
I am looking to put a cat back, bolt on muffler to relieve some back pressure...and so it sounds rumbly
I don't want anything really aggressive sounding.
Something economical, as well.
Any help or suggestions would be appreciated.
Thanks!
I am looking to put a cat back, bolt on muffler to relieve some back pressure...and so it sounds rumbly

I don't want anything really aggressive sounding.
Something economical, as well.
Any help or suggestions would be appreciated.
Thanks!
CF Veteran
Joined: Sep 2011
Posts: 10,447
Likes: 0
From: Frederick, MD
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by D PHILLY
What would a delta 50 series sound like with everything else completely stock? Would their even be a change? Thanks guys!
Senior Member
Joined: Jan 2011
Posts: 730
Likes: 2
From: Joliet, Il
Year: 1996
Model: Cherokee
Engine: HO4.0 I6
So my exhaust has holes in it, it is loose, and well lets just say it is DONEZO...
I brought my XJ back for a recal on the PCM and it turns out my CAT is bad and will be replaced at the cost of the dealership
My question is, when I go to replace everything from the Cat Back can I add 2.5 pipping then? Or does the cat I get have to have a 2.5 fitting on the end? I don't know where the size reduction starts. It is 2.5" all the way to the cat correct?
And don't worry, I'll do my research on which kind of muffler to get. I don't want to be "that guy" and have every one else tell me what to get.
I brought my XJ back for a recal on the PCM and it turns out my CAT is bad and will be replaced at the cost of the dealership
My question is, when I go to replace everything from the Cat Back can I add 2.5 pipping then? Or does the cat I get have to have a 2.5 fitting on the end? I don't know where the size reduction starts. It is 2.5" all the way to the cat correct?
And don't worry, I'll do my research on which kind of muffler to get. I don't want to be "that guy" and have every one else tell me what to get.
CF Veteran
Joined: Sep 2011
Posts: 10,447
Likes: 0
From: Frederick, MD
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by xj guy
So my exhaust has holes in it, it is loose, and well lets just say it is DONEZO...
I brought my XJ back for a recal on the PCM and it turns out my CAT is bad and will be replaced at the cost of the dealership
My question is, when I go to replace everything from the Cat Back can I add 2.5 pipping then? Or does the cat I get have to have a 2.5 fitting on the end? I don't know where the size reduction starts. It is 2.5" all the way to the cat correct?
And don't worry, I'll do my research on which kind of muffler to get. I don't want to be "that guy" and have every one else tell me what to get.
I brought my XJ back for a recal on the PCM and it turns out my CAT is bad and will be replaced at the cost of the dealership

My question is, when I go to replace everything from the Cat Back can I add 2.5 pipping then? Or does the cat I get have to have a 2.5 fitting on the end? I don't know where the size reduction starts. It is 2.5" all the way to the cat correct?
And don't worry, I'll do my research on which kind of muffler to get. I don't want to be "that guy" and have every one else tell me what to get.
Senior Member
Joined: Jan 2011
Posts: 730
Likes: 2
From: Joliet, Il
Year: 1996
Model: Cherokee
Engine: HO4.0 I6
Okay I think I see what you are saying. So is the header 2.25 all the way to the cat and the cat back is 2.25 as well? SO once I get all of my gear together just be sure to get a reducer to put after the cat?
CF Veteran
Joined: Sep 2012
Posts: 1,289
Likes: 0
From: Springfield Virginia
Year: 1998
Model: Cherokee
Engine: 4.0
The cat outlet is 2.25 if you buy a cat back exhaust with a 2.5 diameter you have to get a reducer from a 2.25 to 2.5. If not then don't worry about it.
Senior Member
Joined: Jan 2011
Posts: 730
Likes: 2
From: Joliet, Il
Year: 1996
Model: Cherokee
Engine: HO4.0 I6
Makes sense. Now is there any benefit of going to the 2.5 cat back( I know it is our optimal size) if everything before that is 2.25? Or is that how most of your set ups are?
CF Veteran
Joined: Sep 2011
Posts: 10,447
Likes: 0
From: Frederick, MD
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by xj guy
Makes sense. Now is there any benefit of going to the 2.5 cat back( I know it is our optimal size) if everything before that is 2.25? Or is that how most of your set ups are?
Senior Member
Joined: Jan 2011
Posts: 730
Likes: 2
From: Joliet, Il
Year: 1996
Model: Cherokee
Engine: HO4.0 I6
Noted. And I guess If I ever want to go 2.5 from the headers down I already have the pipes to do it!
As far as buying all of my parts, is it Cheaper to buy all of my pipping separate pick a muffler I like and put it all together myself? Or should I just be looking for an entire kit? I'm trying to save some $$$
As far as buying all of my parts, is it Cheaper to buy all of my pipping separate pick a muffler I like and put it all together myself? Or should I just be looking for an entire kit? I'm trying to save some $$$
CF Veteran
Joined: Sep 2012
Posts: 1,289
Likes: 0
From: Springfield Virginia
Year: 1998
Model: Cherokee
Engine: 4.0
Noted. And I guess If I ever want to go 2.5 from the headers down I already have the pipes to do it!
As far as buying all of my parts, is it Cheaper to buy all of my pipping separate pick a muffler I like and put it all together myself? Or should I just be looking for an entire kit? I'm trying to save some $$$
As far as buying all of my parts, is it Cheaper to buy all of my pipping separate pick a muffler I like and put it all together myself? Or should I just be looking for an entire kit? I'm trying to save some $$$
Senior Member
Joined: Jan 2011
Posts: 730
Likes: 2
From: Joliet, Il
Year: 1996
Model: Cherokee
Engine: HO4.0 I6
I'm excited to have a noise coming from my xj that isn't creaks and cracks or the rambunctious sound of a stock muffler with holes in it... And yes I did just successfully use the word rambunctious.


