Hi all,

From the threads I've been reading, it sounds like the factory exhaust pipe is already 2.5" and has mandrel bends. It also seems like there's not too much difference from one muffler to the next. In general, the turbo absorbs most of the noise, and most mufflers seem to sound good without droning (except for the Aero 2525 which drones if there is not a sufficient length of straight pipe upstream). I've also read some suggestions to stay away from Dynomax mufflers because they are prone to rusting out.

So it seems like all I really need is a straight-through muffler that won't rust. How about a Summit Racing stainless steel muffler?

Summit Stainless Steel Mufflers

It doesn't explicitly say it's straight through, but I can call Summit Racing and ask. It's $70 shipped, which is not too bad. The pretty similar looking MagnaFlow MPE-14316 is $88. I guess it might be worth an extra $18 to go with a name brand... or is it really the same thing?

- Chris

The pipes are not 2.5" all the way thru...they neck down and neck up and neck down. The Magnaflow SS or a Borla SS ($$$) would be a great choice...I know they both sound good too! I think a 3.7L system that would just need a little custom work to get rid of the neck down at the CAT would be the trick.

_________________
Founder of L.O.S.T.
2006 CRD Sport
Mods: GDE Hot Tune w/ 364#@2000rpm/Air Box /3" Str8 Exhaust/ASFIR Alum Skids/245-75R-16 Cooper STT PRO/OME LIFT w/Clevis & 4 Spring Isos/AirTabs/Rigid 10" S2 LED/4xGuard Ctr Matrix Bumper
Drag Strip:Reac=.1078_60ft=2.224_1/8=10.39@64.8mph_1/4+16.46@80.8mph

Hi Darby,

Thanks for your thoughts. Hmm, there's a complete cat-back Magnaflow system for $453. That's a little more than I was hoping to spend. I guess I'll get underneath and see how bad the pipe necks down.

- Chris

You could buy the muffler and use the tailback section...then just have them put in a straight 2.5" pipe to the Cat.

_________________
Founder of L.O.S.T.
2006 CRD Sport
Mods: GDE Hot Tune w/ 364#@2000rpm/Air Box /3" Str8 Exhaust/ASFIR Alum Skids/245-75R-16 Cooper STT PRO/OME LIFT w/Clevis & 4 Spring Isos/AirTabs/Rigid 10" S2 LED/4xGuard Ctr Matrix Bumper
Drag Strip:Reac=.1078_60ft=2.224_1/8=10.39@64.8mph_1/4+16.46@80.8mph

'Course, it's prolly not gonna do you much good on a Jeep, but, fwiw, I have always liked the sound of a big 6-cylinder since I was a kid - hence my Dodge CTD - I've also always been obsessed with the sound of a big-rig as it purred past on the hiway, turbo singing - so of course, I wanted the 3500 pickup to sound similar, if not the same - 'course, they're running long-stroke 1100cuin monster engines at 1200rpm - cain't touch that - anyway, I'd been looking at various 4" ss turbo-back systems, dreading the big price and loud blatty sounds of most of the CTD pickups with a\m exhaust systems - so, if it's gonna sound bad, I ain't payin big bucks for it - I sprung for the Summit 398buck delivered system - arrived in 4 days, and I was ecstatic at first sight and fitup - the fit was perfect, looked good under the truck - bitchin'! - then, temerously, I cranked it over...........and............voila! big-rig city, and then some - it's got that big-cat purr, and the turbo sings it's siren song loud and clear - wotta find! - I now drive with the rear windows open, even on the hottest days, and the a\c cranked up to compensate - I like that SummitRacing system

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

Hi!! I'm using the Summit 30" stainless steel "chambered" muffler. It is 2 1/2" all the way through.
It looks good too! Lol I had it welded on.
Larry K.

_________________
2005 KJ Sport CRD Traded for VW, R32
Patriot Blue
245-70-16 Revos
Fumoto valve
Cat filter, on hold
ScanGage II
2 1/2" straight through chambered muffler(Summit Racing)
Shell Rotella T 5W-40
PML diffrential cover.
L.O.S.T. 075679

I put a Dynomax system on mine. Just a few thoughts. Diesel engines don't rust out exhaust systems like gas engines do. Gas mufflers rust from the inside out. Diesels rot from the outside in. I had an 83 6.2L Blazer. The body of the truck rusted away long before the exhaust system was done. Based on my experience with that truck, stainless isn't that important other than looks.

Diesels engines need the least back pressure muffler there is. That means a straight through design. After the turbo, you want no back pressure. Chambered mufflers are designed to have some back pressure because most gas engines need a little to operate correctly.

The Dynomax went on fine and was a good unit despite not being stainless. The muffler was a welded shell and straight through design. The bends in the pipe were only marginally smoother than the factory system. There are two restrictions in the factory system. First is at the flange near the front. Second is where the pipe meets the muffler.

If I were to do it again I would buy the Dynomax muffler ($50ish), cut the old muffler out and expand the squeezed down end. Use band style clamps to seal or weld it up. The flange could be cut off and a sleeve slipped over. There is already a flexible connection that would absorb any shakes. I don't know why they used the connection they did other than that's the way it was on gas engines. You need to match the in/out pattern and length of the muffler. Summit give a pretty good description of those specs. Or you could hit the easy button and buy a complete system, just get a straight through muffler.

My .02c

_________________
2006 Liberty CRD-SOLD
Dynomax 2.5 exhaust

Oh, and btw, I have looked into one - straight-thru, no internal neck-down reduction, only the thumbnail-sized sound-baffles protruding from the stainless tubing

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

Save your money and put a glass pack or straight pipe on. It really isn't any louder than than the stock muffler. The only difference I can tell is that I can hear the Turbo spooling now.

IMHO why spend $$ for no benefit?

_________________
2005 CRD "Ol' Blue"
Red Ryder carbine-action, two hundred shot range model air rifle with a compass in the stock and this thing which tells time.
My build page- RL Komodo Rear and TJM Front Bumper, armored, lifted, JBA Steel D30, 4.10s and ARB air lockers.

Technical and perceptual differences aside, do you know of a good resource to determine if items like the cat can be removed legally? I.e. The inspection I have once a year is an odb check and a look under the vehicle to make sure the emissions systems haven't been modified.

Dan

Far be it from me to bring the smog cops down on our heads, but for off-roading, a length of 3/4" waterpipe and a good hammer will un-matrix the soot-trap housing for freer flow-thru, if you can ascertain my meaning......................

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

The Summit chambered muffler is straight through and has no more back pressure than a glasspak or other straight through muffler. The chambers are outside of the perforated core and can be seen by looking at the outside of the muffler body. It is NOT a baffled muffler. See the pic in summit's catalog online.
It has a nice deep sound!

LK

_________________
2005 KJ Sport CRD Traded for VW, R32
Patriot Blue
245-70-16 Revos
Fumoto valve
Cat filter, on hold
ScanGage II
2 1/2" straight through chambered muffler(Summit Racing)
Shell Rotella T 5W-40
PML diffrential cover.
L.O.S.T. 075679

If you leave the cat on im sure it isnt loud, but if you cut the cat too and straight pipe it will be very loud....i know

With no cat and a dynomax muffler on i can hear the turbo and it isnt too loud. It is just right

_________________
06 Liberty CRD Sport, Lifetime Sirius Radio, Dynomax muffler(no wimp), EHM, ORM, OME lift, ARB bull bumper
Waiting for time to put on:
cat fuel filter, filter bleeder, clean air supply for egr
Yeah Its A Diesel