exhaust: glasspack vs. muffler
Thread Starter
Seasoned Member
Joined: Jan 2009
Posts: 443
Likes: 2
From: Prescott, AZ
Year: 1996
Model: Cherokee
Engine: 4.0L
Okay... there is already a million threads on here about custom exhaust (I know because I just got done reading them) but none of them really answer my questions so forgive me for starting a new thread, it's not out of pure laziness I promise you.
So my exhaust system broke off my jeep the other day...bittersweet because I need to drop some money to fix it, but that also means an opportunity to upgrade
I'm wondering what option would be best for increasing low RPM torque, I'm not interested in hp as much because I use my jeep for rock crawling, not street racing
So what would be better? a glasspack or muffler? No emissions where I live, so I'm not restricted by that stuff so I have more options.
If I go glasspack, I noticed that I can get them anywhere from 18" to 24", how does that effect performance and/or sound?
If I go muffler, should I do single or dual outlet? how does that effect performance and/or sound?
I've also read in different threads here both sides that I do and do not need to worry about back pressure. Which is it?
Lastly, is upgrading to a larger inlet/outlet going to help or hurt?
Thanks guys.
Dan
So my exhaust system broke off my jeep the other day...bittersweet because I need to drop some money to fix it, but that also means an opportunity to upgrade

I'm wondering what option would be best for increasing low RPM torque, I'm not interested in hp as much because I use my jeep for rock crawling, not street racing

So what would be better? a glasspack or muffler? No emissions where I live, so I'm not restricted by that stuff so I have more options.
If I go glasspack, I noticed that I can get them anywhere from 18" to 24", how does that effect performance and/or sound?
If I go muffler, should I do single or dual outlet? how does that effect performance and/or sound?
I've also read in different threads here both sides that I do and do not need to worry about back pressure. Which is it?
Lastly, is upgrading to a larger inlet/outlet going to help or hurt?
Thanks guys.
Dan
Member
Joined: Nov 2010
Posts: 113
Likes: 0
From: Lumberton, NC
Year: 2000
Model: Cherokee
Engine: 4.0
This doesn't help much but, my friend has a ZJ with a 4.0 18" (I think) glasspack and it sounds like a bumblebee muffler kinda..and I don't think you would have to worry about back pressure because thats normally only with straight pipes..and large diameter pipes will be louder but also I would think(just using common sense) it would have better exhaust flow..
Senior Member
Joined: Jun 2010
Posts: 689
Likes: 2
From: Payson, UT
Year: 1993
Model: Cherokee
Engine: 4.7L I6
If you want my 2 cents...i had a glasspack for a year or so and i gotta admit i loved the sound and it gave me some more power, but mostly hp it seems...later when i got the money i got a borla cat back system...and i gotta say, the increase in low end torque AND hp was pretty amazing, it looks good and sounds real deep like a Jeep should, and my tailpipe even says Jeep on the top, haha...long story short, both are good, but the muffler and catback system would be my choice!
Thread Starter
Seasoned Member
Joined: Jan 2009
Posts: 443
Likes: 2
From: Prescott, AZ
Year: 1996
Model: Cherokee
Engine: 4.0L
Thanks for the advice, I think the borla is kinda out of my price range for a quick fix, maybe I can just run a straight pipe till I can save a little more if it really is worth it for the extra torque.
Senior Member
Joined: Jun 2010
Posts: 689
Likes: 2
From: Payson, UT
Year: 1993
Model: Cherokee
Engine: 4.7L I6
Trending Topics
Thread Starter
Seasoned Member
Joined: Jan 2009
Posts: 443
Likes: 2
From: Prescott, AZ
Year: 1996
Model: Cherokee
Engine: 4.0L
yeah, and I can get a welded turbo style muffler for about the same price. just trying to figure out which is the better option. A full catback system would be best if I could afford it...but if I spent that much on a shiny exhaust system I'll just be more disappointed when I scratch and dent it on a trail (and that's *when*,not *if*)...haha
Senior Member
Joined: Jun 2010
Posts: 689
Likes: 2
From: Payson, UT
Year: 1993
Model: Cherokee
Engine: 4.7L I6
yeah, and I can get a welded turbo style muffler for about the same price. just trying to figure out which is the better option. A full catback system would be best if I could afford it...but if I spent that much on a shiny exhaust system I'll just be more disappointed when I scratch and dent it on a trail (and that's *when*,not *if*)...haha
CF Veteran
Joined: Aug 2010
Posts: 2,038
Likes: 4
From: DIRTY SOUTH
Year: 1991
Model: Cherokee
Engine: 4.0 ho
i got a 27" thrush glasspack,and i love it,i hear my exhaust pop when i let off the gas,no power difference really,that i could notice but i love the sound,mine will actually lope sometimes,and i love it
Thread Starter
Seasoned Member
Joined: Jan 2009
Posts: 443
Likes: 2
From: Prescott, AZ
Year: 1996
Model: Cherokee
Engine: 4.0L
I'm thinking of doing a very similar setup, maybe just with a turndown after the muffler instead of going all the way back. did you notice any torque gains at all?
Thread Starter
Seasoned Member
Joined: Jan 2009
Posts: 443
Likes: 2
From: Prescott, AZ
Year: 1996
Model: Cherokee
Engine: 4.0L
I also just read on another forum that there is a correlation between back pressure and torque vs. hp, like that more back pressure = more low RPM torque and less high end hp, and that free flowing = less torque and more high end hp. Can anyone back this up?
does that mean that the longer 24" glasspack would give more torque/less hp and the dual outlet muffler more hp/less torque?
does that mean that the longer 24" glasspack would give more torque/less hp and the dual outlet muffler more hp/less torque?
CF Veteran
Joined: Aug 2010
Posts: 2,038
Likes: 4
From: DIRTY SOUTH
Year: 1991
Model: Cherokee
Engine: 4.0 ho
its not true,if it was then you wouldnt see drag cars wit straight pipes,it was just a rumor that was spread so people would keep mufflers and cats on there vehicles to pass emissions and be more "green"


