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Last Post 03 Dec 2008 02:54 PM by  01 FS Z28
Best Performing Duramax Exhaust?
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gtldvm
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28 Nov 2008 10:07 PM

    In today's market, and the fact that I have 3 payments left on my 2005 GMC 2500HD Crew Cab 4X4 Short Bed Duramax Diesel, I'm looking forward to having a really great truck WITHOUT a truck payment! But now that I'm racing a lot nationally, I am putting a pretty fair amount of towing mileage. To date, the only changes I've made to the truck is the "Juice w/ Attitude" from Edge, and a K & N filter/intake. I have heard that a new exhaust would give me better performance AND fuel mileage per gallon. I'm sure there are a bunch of Duramax owner's on this forum that could tell me what has worked and why.

    I look foward to further modifying my truck and enjoying it for another racing season.

    thanks in advance,

    Impala SS AutoXer
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    01 Dec 2008 05:35 PM

    I have an 06 ExtCab ShortBed 2WD with the Duramax. I am using an MBRP Catback, been pretty pleased with it. Not a whole lot louder than stock, despite being bigger (4" vs 3.5") and the muffler is, well, let's just say a baseball would fall right thru it!

    Picked it up lightly used off Craigslist, "cheap" because it was originally set up with an aftermarket exhaust brake on a crewcab truck (i.e. longer and hacked a bit right at the front). Was all prepared to have to fabricate things to make it work, ended up because my truck is shorter the "fab work" consisted of just shortening the front pipe (i.e. few minutes with a cutoff wheel) and bolting it it!

    The MBRP has help up well (it is stainless) and looks great. Not going to claim miracles on either HP or MPG, but it didn't hurt on either.

    autoxn
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    01 Dec 2008 06:19 PM

    Greg,

    Go with the MBRP turbo back. Your truck will thank you for it. Heck, your truck probably doesn't even have cat's anyway.

    Jr.

    DSPBMW
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    01 Dec 2008 06:41 PM

    The 05's can get really hot (egt's). When the attitude monitor went in did you have the pyro hooked up?

    The exhuast is going to net you less EGT's. That's about it.

    The 05 I had had the exhuast removed before the cat. Dumping out of the down pipe. With a stock tune the truck was building quite a bit of boost at IDLE.....Which made the truck perform much better all the time......I attributed the performance gain to the increased fueling when underboost.....

    Only tune I ever tried was a Bully Dog hand held it the thing smoked so bad I couldn't drive it..........

    gtldvm
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    01 Dec 2008 10:26 PM
    DSPBMW wrote:

    The 05's can get really hot (egt's). When the attitude monitor went in did you have the pyro hooked up?

    The exhuast is going to net you less EGT's. That's about it.

    The 05 I had had the exhuast removed before the cat. Dumping out of the down pipe. With a stock tune the truck was building quite a bit of boost at IDLE.....Which made the truck perform much better all the time......I attributed the performance gain to the increased fueling when underboost.....

    Only tune I ever tried was a Bully Dog hand held it the thing smoked so bad I couldn't drive it..........

    Yes, I have the pyrometer hooked up, and it does reach the max pretty quickly when pulling a big hill...not a problem is the truck downshifts, but if not then it bucks pretty bad.

    What is MBRP? What does it stand for?

    DSPBMW
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    01 Dec 2008 10:47 PM

    There is a factory reflash that will prevent the bucking. Might be worth pulling the Edge, and taking it in for a reflash.

    MBRP is a brand of exhuast......You honestly won't gain much of anything except lower EGT's.

    When I had mine the Summit exhuasts got pretty good reviews and was a great value. They offer a 5" Which I would go with vs spending all that money for an exhuast .5" bigger than stock......Fitment last I heard was fine but a 5" tailpipe does interfere with the spare just a little. If you have anything bigger than the stock 245's on the spare location you would have to remove it.

    gtldvm
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    01 Dec 2008 11:33 PM

    Thanks for the info.

    I had heard there were gains in performance and economy with some of the catback systems. anyone realized such? obviously you've experienced some improvement. Is the improvement worth the investment in a new exhaust, and what should I expect to have to pay?

    gtldvm
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    01 Dec 2008 11:36 PM
    DSPBMW wrote:

    There is a factory reflash that will prevent the bucking. Might be worth pulling the Edge, and taking it in for a reflash.

    I already had the reflash done...3 years ago. It still bucks, but very rarely, and no where near as it used to. I think the term I heard for it was "turbo-bark", or something like that.

    01 FS Z28
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    02 Dec 2008 04:14 PM

    Greg--

    I've got access (easy) to a lot of diesel truck stuff. Exhaust wise Magnaflow, MBRP (which is a Canadian company the initials stand for something I don't recall... nice stuff). HOG Performance, Diamond Eye, and Banks just to name some of the most popular ones.

    You have a lot choices in material (aluminized, 409 or 304 Stainless), as well as options on complete turbo-back systems, or cat-backs. Most go turbo back as the stock downpipe is kind of crappy (small). And then there is the lovely necked down manifold on (as I recall) the driver's side. Not part of any system, but there are non-necked down replacements available which help boost and lower EGT's too. The cost depends on just how much you want to do. There can be some gains from the exhaust because it's obviously more efficient to not have the exhaust choking the system. But most gains in economy will come from a good flexible tuner that can change things like injection timing. I see you have an Edge Juice w/Attitude already, so that's take care of (and works well). Since the intake is done, all that's really left under the "easy" category is exhaust stuff.

    gtldvm
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    02 Dec 2008 10:39 PM
    01 FS Z28 wrote:

    Greg--

    I've got access (easy) to a lot of diesel truck stuff. Exhaust wise Magnaflow, MBRP (which is a Canadian company the initials stand for something I don't recall... nice stuff). HOG Performance, Diamond Eye, and Banks just to name some of the most popular ones.

    You have a lot choices in material (aluminized, 409 or 304 Stainless), as well as options on complete turbo-back systems, or cat-backs. Most go turbo back as the stock downpipe is kind of crappy (small). And then there is the lovely necked down manifold on (as I recall) the driver's side. Not part of any system, but there are non-necked down replacements available which help boost and lower EGT's too. The cost depends on just how much you want to do. There can be some gains from the exhaust because it's obviously more efficient to not have the exhaust choking the system. But most gains in economy will come from a good flexible tuner that can change things like injection timing. I see you have an Edge Juice w/Attitude already, so that's take care of (and works well). Since the intake is done, all that's really left under the "easy" category is exhaust stuff.

    Sounds very interesting, Sam. Can you provide me quotes for the turbo back systems? I never do anything half-way...I just wait until I can afford what I want. It's cheaper than regrets. Let me know if you need my email address if you want to do this privately.

    01 FS Z28
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    03 Dec 2008 01:55 PM
    I'm on it... It'll take me a little time to get all the various option together and typed up.
    01 FS Z28
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    03 Dec 2008 02:54 PM
    I sent you a PM Greg... Feel free to call me if you have any questions.
    You are not authorized to post a reply.


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