DIY exhaust upgrade - newbie help - Chevy and GMC Duramax Diesel Forum
Aftermarket Mods. Discuss what Mods are right for you.

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post #1 of 5 (permalink) Old 01-22-2020, 11:33 AM Thread Starter
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DIY exhaust upgrade - newbie help

Hello all,

New to the forum, and new to owning a duramax. (2005 sierra 2500 HD single cab)
just bought this truck off of a company where i manage the fleet, it is impeccably serviced and is at 1,340,000 kms.

I'm not going to sink a ton of money into the truck. the only "big" thing i want to change is the exhaust. Never owning or modding a diesel before, is there anything i need to know? Can i cut out out a certain portion and install a glasspack or something simple like that? will it cause any issues? what part should i cut out?

I'm going for super cheap, diy, no or minimal welding (I don't own a machine), not wanting showroom quality, just a good sound and the minor performance boost that may come with. I'm aware of "you get what you pay for", as I've modded lots of other vehicles. Hoping for some knowledgeable insight.

Thanks in advance!
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post #2 of 5 (permalink) Old 01-22-2020, 11:36 AM Thread Starter
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I just noticed I posted in the wrong area. Sorry, not sure how to fix it now.
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post #3 of 5 (permalink) Old 01-22-2020, 12:16 PM
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the only "big" thing i want to change is the exhaust.
800k+ miles....impressive.

just a good sound and the minor performance boost that may come
Performance gain on a stock truck....minimal, if any, IMO. (unless it's a Ram....there, everyone knows loud = fast )
I think you'd see more gains with swapping out the flat/restrictive down pipe with one of Rick's inexpensive 3" ones.

Good sound? Like an annoying drone out on the hwy?
To each their own, and that's okay. Straight pipe back, aft the DOC, maybe?

But many have changed their minds afterward, tiring of the hwy drone, adding an oversized muffler back into the mix.

I'd try and leave the DOC though, drastic difference in exhaust smell with it, vs without it.
Fit always seems to be a point of frustration with aftermarket exhaust brands, so do your research.

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Last edited by Hook'em_Horns!; 01-22-2020 at 12:18 PM.
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post #4 of 5 (permalink) Old 01-22-2020, 01:35 PM
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You can mod your exhaust without issue, won't cause a CEL or anything. Wouldn't recommend a glass pack, just do straight exhaust(no muffler). Do an aftermarket down pipe if you want to do a little more work, makes a solid difference in sound. No welding required with any of the kits I have seen, they all use the factory hangers.
Personally, I've had my truck straight piped for around 9 years now and still love it. Not many sounds that are better imo.

With some stuff.
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post #5 of 5 (permalink) Old 01-23-2020, 07:39 AM
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I pretty much agree with Hook, except for the downpipe.
I went for all the hoop-la with the gains going with aftermarket downpipe vs stock, stock is oval shaped, very close to the same total circumference as aftermarket, not enough to make any difference.
Absolutely no changes with anything not even EGT’s, only changes was lighting up my wallet and taking up to a half day installing.

Straight pipe is kool but after a while the excessive drone and exhaust stink will get annoying to most.
There’s been a few that has put the stock cat/doc back on after straight piping so they can breathe and talk in a normal voice to other people in the cab.

A few threads recently people wanting to know if a aftermarket cat will help, NO IT WON’T,
I’ve already tried this.
Me included after 5 years of annoying drone and exhaust stink, first installed the FTE resonator/muffler on to tone down the drone then eventually had to put my stock front pipe with cat back on to tone down the exhaust stink, no power loss or EGT changes.

I found that the stock muffler and DPF (you don’t have) are the most restrictive.

Anyone that claims they don’t notice any differences they have to : something or or even both, at least while they’re driving.

I’ve come to a conclusion over the years when people make all these awesome gain claims on stuff they just want others to be foolish enough to spend the time and money like they did.

If you leave the stock downpipe and cat then go straight exhaust catback you won’t have to worry about having a muffler.
IMO with my experiences only replace the downpipe if your is having issues like exhaust leaks.
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Last edited by D_R_C; 01-23-2020 at 07:43 AM.
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