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My glass pack style 4" muffler got old quick. A little too loud cruising and way too loud towing. My ideal muffler would be low restriction, throaty under acceleration, yet quiet when I hit the cruise button. Installed one yesterday that fit the bill. Donaldson #M085171. 8.5" OD with a 35" body. +/- $65. A tight fit, but my muff shop did a good job of jamming it in there. It's a straight through design with a perforated inner core. It has a four section perforated cone in the middle to divert some flow through the outer perforations. Looks to me like it's designed to let you open up the center a little or a lot easily. Custom tune it to whatever noise level you're willing to put up with. I'm happy....kids are peeved. They used to hear me coming a mile away. Now I can sneak up on 'em.
 

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Twinscrew,


A few of questions for you,


1. Is there any noticeable drone in the cab?


2. How is the sound when towing?


3. Can you hear the turbo whine?


4. Do you feel there was any increase in power?


5. Has the wife noticed any difference and if so how much?


6. Do you have an EGT and did you see any drop in Temp.?
 

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Forgot one!


7. Any pictures?
 

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Mike, What are you running? I'm looking for a replacement for the stock muffler, a little more free flowing than stock, but just as quiet.Edited by: aketay
 

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Sounds good (pun intended). Too long for my short box with the exhaust brake, though. Have you tried it towing or with a heavy load yet?


--Rob
 

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Ran across this searching. This is exactly the same thing I'm looking for. Sneaking up on 40, and the days of loving every day daily driving a built 455 GTO with glass packs are long gone. Like some of the other posters, I would love my SWB 4x4 CC to have a nice mellow tone but no drone and no "blat-blat-blat" under load (my neighbors mildly turned up Cummins with some after market 4" glass pack looking thing). But, on the other hand, I would like to be able to easily tow my 15k GVW in Lvl 2 w/o defueling or having to watch the EGT. The Donaldson sounds good (yeah, pun) but I don't see any clear answers about the effect on EGT and turbo spool up. Does that deflector make a significant difference in the performance issues?


On a similar note, my exhaust guy suggested just putting a 4" muffler on my stock 3.5" exhaust. He says he's done that before and had people come back for the full exhaust only to see *no* noticeable change in perf or EGTs with the 4" pipe. He also says the stock exhaust is hard to beat for quality (I agree from what I've seen) and the benefit is just not worth swapping to kits that generally have lower quality metal to boot (unless way more cost to match OEM). What do you guys think of using a 4" muffler on the stock pipes? Effect on noise or perf? I especially want to hear from anyone who has mixed the two. At least it will be ready for larger pipes if I decide to go that far.
 

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Ran across a post by Idle_Chatter on using a "4" Magnaflow 20" stainless straight-through muffler into my stock system". But still no info on exact effect on EGT and turbo spool up, or even noise levels.


Other good info on that thread by following the link.


http://dieselplace.com/forum/forum_posts.asp?TID=2294&KW=muffler
 

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There is more exhaust noise noticable in the cab - but it doesn't bother me. There's a drone at 1500 rpm, but seems to peak only at that rpm and there's not many situations where you stay at that rpm range for any long periods of time. My EGTs went down 100-150 degrees "across the board" (all speeds) with the free-flowing muffler. The audible change in the turbo is negligible and I rarely noticed the turbo before the muffler unless specifically listening hard for it and it's the same with the Magnaflow. Been nearly 16 months since the mufflerectomy now and I'm totally pleased.
 
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