Glass Pack muffler on the 3.7Ltr.....?

Just kicking around an idea here. Will be going through emissions inspection tomorrow morning with my '05 KJ Renegade, after which I'll be good to go for another 2 years. I'm presently running with a Thrush Welded Hi-flow muffler connected to the stock exhaust piping.....(have to have a tail pipe in order to get emissions testing)......

Once I'm clear of this and have my 2 year sticker on the windshield I was thinking about returning the exhaust back to the way I had it with a turn down pipe out of the muffler and eliminate the bends and pipe diameter changes in the tail pipe. However since I'll have to reinstall the tail pipe again in another 2 years for the next emissions inspection, I thought about just taking it off from the muffler back, keeping the whole assembly together, and slipping on a glass pack with a turn down pipe, and run with that.

I've seen photos on here of others who are running with glass packs, and would like to hear from them. I don't assume I'll see any improvement in performance over the Thrush Hi-flow I have now, I'm more concerned with sound quality. How does the 3.7Ltr sound with just a glass pack as compared to the Thrush Welded, Dyna-Flow, or Flowmaster type mufflers.

What brand / type of glass pack do you have, and how would you rate the sound quality......?

As of now I get a low rumbling, almost a small block V-8 sound, moderately low noise level, what I don't want is for it to sound like a rice burning tuner, or an old tank.....

I am running a Thrush glass pac 28in overal . Think it sounds good. And the price is right.

ridenby said:

I am running a Thrush glass pac 28in overal . Think it sounds good. And the price is right.

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Thanks ridenby, couple of questions......

Did you cut the stock pipe back before the reduction and go with a 2" muffler...?

Use a turn down pipe on the business end......?

How bad is the drone inside, especially at highway speeds.....?

Notice any ill effects from having no back pressure on the engine.....?

And did you wrap yours with exhaust wrap, or just run it as is.......?

SurfGuitar141 said:

Thanks ridenby, couple of questions......

Did you cut the stock pipe back before the reduction and go with a 2" muffler...? Cut the third cat out,21/2" in and out

Use a turn down pipe on the business end......? Had it spliced in to the tail pipe for a while,replaced glas-pac with new glas-pac(rocks are ******* stuff)currently running straight out glas-pac.

How bad is the drone inside, especially at highway speeds.....? Drone? I run mud tires,currently Super Swamper LTB's. I can hear engine,wouldn't call it drone though.

Notice any ill effects from having no back pressure on the engine.....? Not that I could tell,it pops,gurgles some in Low range going down hill.

And did you wrap yours with exhaust wrap, or just run it as is.......?as is,was concerned about mud,water causeing it to rust quicker.

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inserted? answers. :smokin:

As for the question of sound, also check out youtube. I have found cherries on there. I would look up a link though I am at work.

The only thing I can find locally from pep Boys is a Magnaflow glasspack, and they're getting a hundred bucks for them. Not like they're stainless steel either, just regular exhaust grade heavy steel.....un-painted at that.....

Do to the new self inspecting regulations recently passed here in New Jersey, I was informed on good authority that if I modify my exhaust in any way that does not comply with NJ motor vehicle code, and get pulled over for a roadside inspection, I could be fined heavily for every infraction.

This means whatever I do muffler wise, will have to include being connected to the stock tail pipe like it is now. That means going from an off set connection at the muffler, to a straight through connection, assuming there's enough play in the tail pipe to accommodate it......

Mission accomplished......

Made a few phone calls and found an Auto Zone not far from home with the right model Thrush Glasspack in stock.....(and they only had one)....

A couple of new 2" clamps, and a piece of 2" extension pipe, and the new glasspack is in.......


My assessment is, the glasspack sound quality is identical to the Thrush welded muffler, only slightly louder. Running it straight without the tail pipe attached it's a little too loud, not so much for me, but the wife would really hate riding in the Jeep with me had I left it that way.
A piece of 2" extension pipe got me to the stock tail pipe, and with the sound diverted to the back, cab noise is greatly reduced, yet it still makes plenty of noise on the outside.
Much like the Vance & Hines exhaust on my Harley, the glasspack really comes to life when I go heavy on the gas peddle. No sooner than I was done installing it, I got a fire call for one of the local schools, responding to the fire station needless to say.....I was on it pretty hard, and I turned a few heads on the way.....

Thanks to ridenby for your advice.......

Your Welcome.

So now it sounds like a KJ with a shot muffler!

Not at all,have run NO muffler,sounds like complete shit,with tail pipe sounds better than any high buck "system" ever heard,no tail pipe just puts more sound in cabin.

Sure no one cares, but you can get glasspack style Magnaflow (stainless)..

Okura_hubby said:

Sure no one cares, but you can get glasspack style Magnaflow (stainless)..

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There's several on the market that will sound closely the same Okura_hubby, Cherry Bomb has several models for different sound levels and applications, as does Thrush/Walker, Dynaflow, and Magnaflow. I could have ordered this very same Thrush glasspack in stainless, but the cost is 100 bucks compared to the $29.95 I paid for this one with red powder coating, and there would be no difference in sound level or quality. If my entire exhaust system was stainless I would see the benefit, but since it's not, the price doesn't justify it's worth....