Exhaust Options/Opinions

[Iggy913]

Gentleman,

I have a 923A2 and I cannot be alone in thinking these trucks are far too quiet for their monsterous size and overall appearance. I understand the military wants them as quiet as possible as to not alert anyone to their presence, but as a civillian owner of one of these giants I'd like the sound to go along with the looks.

The exhaust system as a whole looks very simple and easy to change and here is my plan, please feel free to comment and offer suggestions:

Cut factory 4" exhaust under the cab, or unbolt it at a logical place if there is one to be found. Assuming I cut the pipe off just under the cab I would then install a 4"-5" adapter, then a 5"-6" adapter. 6" is overkill but in my opinion it looks right with the massive size of everything else.

From the 6" adapter I would run a 6" 90 degree elbow to bring the pipe out and pointed skyward to a 6" curved stack ending in the same place as the factory stack. I would also keep the factory exhaust cover in place to prevent any issues and give a "factory" appearance to my modification.

I do have a few questions:

First will a 6" pipe fit under the cab? It looks like there is plenty of room but has anyone done it? I could always run 5" to the back of the cab then increase to the 6" stack if neccessary.

Second, why is the factory stack at an angle? It doesn't make sense that it would be done like that, was that just easier than bringing the exhaust closer to the edge of the cab and straight up? I don't have a top on my truck so does that angled stack somehow keep exhaust out of the back of the truck if there was a top on it?

 

[porkysplace]

Search " 923 straight pipe " you will have plenty of reading and ideas.

 

[61sleepercab]

WHAT====== SPEAK UP======CAN'T HEAR YOU====TURN UP THE RADIO AN TV !!!!!!!!! If you want to change tone, try a dirt track straight thru header muffler which will make truck sound better. You will not believe difference they make in a open header 350 V8 dirt car sound. Check out Speedway.com

 

[73m819]

My 4" straight piped m819 is so loud under load, that my wife KNOWS when I leave the SSGAR (2 hours away)

 

[plode]

It's at an angle so it clears the cargo cover, and doesn't spew hot smoke all over it...potentially gassing troops

 

[plode]

And assuming your truck has the 8.3L, the turbo really quiets down the exhaust as it is, so it's not like straight piping a NHC-250 or a multifuel engine.

 

[HETvet]

I would go 4 inch straight pipe from the turbo back. Then turn up the fuel and that should give you the sound and look I think your after

 

[Iggy913]

Thank you all for the opinions and suggestions. I ended up ordering various exhaust tubing from an online source and will be making my own exhaust stack as soon as it arrives.

For what it's worth, if you don't have a good source for exhaust tubing or the desire to make the system yourself, you'd be hard pressed to make your own for less than the vendor here "Those Military Guys" can sell you one for. The only reason I'm not using their system is I like the look of the larger diameter pipe, otherwise it looks like a very well made system.

 

[peteybabes]

sorry to dig up such an old thread, but how did this go for you Iggy913? I'm considering the same thing...

 

[Iggy913]

Like I mentioned above, I ordered various exhaust piping from an online retailer and made my own. I removed the factory exhaust stack at the joint just behind the cab and used reducers backwards to increase pipe diameter from 4-5 then 5-6. I also used a 6" curved stack to complete the exhaust. In the end my new exhaust exits at the identical location as the factory pipe but it is 6" vs 4". I ended up having to make some spacers out of 1/4"x1" stock from Home Depot to push the factory heat shield out further to accommodate the larger pipe, super simple to do overall and it looks much better than the small factory piping, heck the intake pipe on the other side is 5" so at least it's reasonable to see the exhaust so big.

Now in the end I will say as others have, not having a muffler isn't the most pleasant experience. I'm going to look into a slip in muffler that will just drop into the exhaust stack from above. It's no problem on short trips but anymore than 30 minutes or so and it gets a little too much for me, I'm a little older now and don't enjoy the open exhaust right behind my head, had it exited down or further back it wouldn't have been an issue, but the soft top does little to isolate you from the noise.

 

[peteybabes]

Like I mentioned above, I ordered various exhaust piping from an online retailer and made my own. I removed the factory exhaust stack at the joint just behind the cab and used reducers backwards to increase pipe diameter from 4-5 then 5-6. I also used a 6" curved stack to complete the exhaust. In the end my new exhaust exits at the identical location as the factory pipe but it is 6" vs 4". I ended up having to make some spacers out of 1/4"x1" stock from Home Depot to push the factory heat shield out further to accommodate the larger pipe, super simple to do overall and it looks much better than the small factory piping, heck the intake pipe on the other side is 5" so at least it's reasonable to see the exhaust so big.

Now in the end I will say as others have, not having a muffler isn't the most pleasant experience. I'm going to look into a slip in muffler that will just drop into the exhaust stack from above. It's no problem on short trips but anymore than 30 minutes or so and it gets a little too much for me, I'm a little older now and don't enjoy the open exhaust right behind my head, had it exited down or further back it wouldn't have been an issue, but the soft top does little to isolate you from the noise.

i have the hard top which does quite a bit to keep noise down when the windows are up, do you have a sound clip or video of how it sounds?

 

[fattboy123456]

Cut my exhaust off at the back of the cab
Purchased a 4" 90 Large radius
then a 7" stack with a 4" inlet 36" tall i belive

 

[jerry v]

looks cool i like it

 

[Iggy913]

I do not have a sound clip but it's extremely loud inside and out. The sound itself is fine, I drive a Dodge with a Cummins in it everyday so the straight 6 diesel sound is familiar to me. However with the soft top and the proximity of the exhaust stack so close to the back of the cab it is simply too loud for me during extended driving. Maybe if you used 4" exhaust the sound would be quieter but with the 6" tubing it's plain old loud.
They do make drop in muffler "cores" for lack of a better word that fit inside the exhaust pipe itself which I will be trying just to take some of the sound out. If I could drop it even a few decibels I would be happy. On the good side of things there's no doubt it looks better than the smaller factory pipe, and there is no doubt there is a performance gain to be had. I did the smaller air filter swap from "Those Military Guys" as well as tweaked my fuel pump at the same time. With all three changes the truck is much more powerful feeling, and sounding.

 

[peteybabes]

I do not have a sound clip but it's extremely loud inside and out. The sound itself is fine, I drive a Dodge with a Cummins in it everyday so the straight 6 diesel sound is familiar to me. However with the soft top and the proximity of the exhaust stack so close to the back of the cab it is simply too loud for me during extended driving. Maybe if you used 4" exhaust the sound would be quieter but with the 6" tubing it's plain old loud.
They do make drop in muffler "cores" for lack of a better word that fit inside the exhaust pipe itself which I will be trying just to take some of the sound out. If I could drop it even a few decibels I would be happy. On the good side of things there's no doubt it looks better than the smaller factory pipe, and there is no doubt there is a performance gain to be had. I did the smaller air filter swap from "Those Military Guys" as well as tweaked my fuel pump at the same time. With all three changes the truck is much more powerful feeling, and sounding.

I have 4" straight through at the moment, and it is loud, but i'm wanting to get a the deeper roar that 6" would get me...

I'm also considering doing a "K&N-style" intake under the hood which would mean that the intake stack is WAY shorter, and hopefully much more effective (i could still go 5-6 feet deep in water without worries although i have no intention of doing so...) I also think that with a tiny bit of modification i could make it a "Ram-Air" by removing the map light above the left headlight and plumbing the intake straight to that vicinity...

 

[Moto2four]

A straight stack is going to be uncomfortably loud and annoying. I straight piped mine with 6in straight back to the middle of the bed.

 

[peteybabes]

A straight stack is going to be uncomfortably loud and annoying. I straight piped mine with 6in straight back to the middle of the bed.

That's a great idea. i can also smoke out the guy next to me a little easier