Cutting the muffler off a Duramax
- Thread starter Abindl
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Can't speak for a D-Max, but on 2 of my 5.9 Cummins', it sure seemed like it helped. Sorry I couldn't help ya....
probably wont help the hp rating, but it should keep your egts down
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5" straight pipe from downpipe back helped in teh power department, but not much. Brought the mileage up ~ 2mpg too.
thats what i would say
I had my dodge straightpiped with the stock piping and didnt notice much of a performance difference(other than it sounded fast). I put on a Diamondeye 4" turbo back and it helped my EGT's...too much fueling, not enough boost. In the long run, probaply not much of a noticable difference, but reducing the restrictions in BOTH intake and exhaust WILL help...
my $.02
himarker
my $.02
himarker
i cut my muffler off on mine and piece of pipe put in place, cant say any major hp increases but lower EGT's, builds boost littler quicker and sounds effin siick.
cut it off
cut it off
went from stock exhaust to bullydog cat back including muffler.. didnt feel or hear chat..
took out the cat and muffler and like highmarker said, it sure sounds fast.. also, you can really hear the turbo spool up now!!
took out the cat and muffler and like highmarker said, it sure sounds fast.. also, you can really hear the turbo spool up now!!
I dunno if you're talking about a Dmax, but if you put 5" straight on a Cummins you'll actually lose a little bottom end power unless you're around 500hp before.
and 2 mpg from exhaust?
I had a 2005 Chevy Duramax. 4" From turbo back, no muff, no cat. I saw 1mpg increase when i did that mod. (i was driving 90 miles a day on the highway @ 68mph). As far as power? who knows, but it sure sounded sick!!! Nothing like romping on the pedal passing cars and hearing your exhaust echo off the car...
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I have three years worth of fueling records to prove it.and 2 mpg from exhaust?
Pre-exhaust:
17-Jun-2008 128430 10.0 gallons $45.79 12.5mpg
22-Jun-2008 128772 18.3 gallons $84.01 18.7mpg
26-Jun-2008 128964 10.2 gallons $47.11 18.8mpg
01-Jul-2008 129277 19.7 gallons $89.84 15.9 mpg
That averages 16.475 miles per gallon
Post Exhaust
17-Jul-2008 130485 14.0 gallons $64.39 23.6mpg
18-Jul-2008 130736 14.0 gallons $64.39 17.9mpg (no the price and gallons isn't a typo)
19-Jul-2008 131140 21.0 gallons $97.84 19.2mpg
26-Jul-2008 131435 16.0 gallons $74.24 18.4mpg
That averages 19.775 miles per gallon.
Sure it lost some bottom end, that always happens when you open up exhaust no matter the application.
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shortstop20
Well-known member
Did you buy a whole kit of some sort of just fab it up yourself? Thinking about doing this to mine, I've heard similar things from other people.
straight pipe it right out the back and your turbo/exhaust will push you along lol
Heres a place the sells good kits for under 400 dollars shipped.
http://www.powerbypoole.com/exhaustkits.html#duramax
dont know about dmax but i cut the muffler off my pstroke and welded a piece of pipe in its place, it spools up faster now and lowered egts 100 degrees. sounds way better but i like em loud, just like my sleds
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Took it to the local exhaust shop and got screwed, charged me 3x what you could do it for yourself, but it was all mandrel bent and welded up
If you are going to straight pipe a duramax, do a 4". The only thing a 5" exhaust on a duramax gains you over the 4" (other then a lighter wallet) is more resonance, which really isn't a good thing.
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