4.0 muffler choices

shawn

shawn

running dog lackey of the oppressor class
Administrator
Joined
Mar 13, 2005
Location
Raleigh, NC
Let's talk dumb shit.

I've got a Flowmaster 50 on one Jeep. Sounds nice at idle (if loud), sounds all right at WOT. Sounds terrible from 2000-3000 rpm. Droning bitch. But it's built like a tank and doesn't care if you poke it with rocks, pointy sticks, or much of anything else.

I've got a factory Mopar on the other one. It sounds like an 84 Oldsmobile Delta 88 would sound, if Olds put BMW motors in their cars instead of SBCs. It's fine, but it's also probably on its last legs. I'm going to need to put a tailpipe on this one soon, so will probably replace the muffler at the same time.

So... what else is out there?
 
I've always liked a short glasspack style muffler on a 4.0. I use them on longarmed TJs frequently. They are cheap, sound pretty good and little drone.
 
Maybe somebody knows if still available. Mid 60s Corvair turbo,short case,2 1/2 in 2 1/4 out, quiet idle didn't draw much attention but got loud at WOT. Not much back pressure and two of them on a sbc with headers was ideal
 
I liked the glass packs on the buggy. While it's no 4.0, they did sound pretty good and didn't have much of a drone sound
 
You're wanting a very specific thing that not many aftermarket mufflers address, btw.

Basically you're looking for sound attenuation over a narrow band of frequencies - enter the Helmholtz resonator or 1/4-wave resonator design.
 
I have gone through just about every muffler and exhaust setup under the sun and my absolute favorite setup on my XJ is a hi flow cat with 2.5" piping all the way back to 2.5" magnaflow muffler to a 2.5" tailpipe with a nice stainless steel tip with a 3.5" outlet.

Its not loud at idle but sounds really good WOT and cruising.
 
I wish I knew what mine was, but I absolutely love the way it sounds. It isn't loud but has a great burble at idle. I'm really hoping I can duplicate the sound when I upgrade my exhaust.
 

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If you're not running a full tail pipe right now, that will make a huge difference. I tried my FM50DF with a turn down and hated it. With a full pipe exiting right under the bumper and it is a night and day difference.
 
Hood stack? Lol

I'd go with another Flowmaster and stuff a glasspack in front of it to act as a resonator. Should help pull some of that drone out.
 
StrokedWJ said:
If you're not running a full tail pipe right now, that will make a huge difference. I tried my FM50DF with a turn down and hated it. With a full pipe exiting right under the bumper and it is a night and day difference.
Click to expand...

Both TJs have a solid tailpipe that extends to the rear bumper.

The one with the Flowmaster is still loud as fuck.
 
I'm a big fan of the DynoMax Ultra Flow welded series. I've got a dual in/dual out on my Silverado with high flow cats and 3" pipe. Very mellow tone, but sounds damn good. No drone in the cab and the pipes are dumped about a foot and a half in front of the rear bumper.

MagnaFlow and DynoMax are both made by Walker, if I'm not mistaken, and they make some great products. I'm VERY picky about exhaust and I'm very satisfied with the DynoMax. It replaced Flowmaster 40 series, which sounded good, but I picked up noticeable power when I ditched them.

They make them in round cases or oval cases too.

http://www.summitracing.com/search/...o-welded-mufflers?autoview=SKU&ibanner=SREPD5
 
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