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New Duramax Owner

1734 Views 6 Replies 4 Participants Last post by  TYREBOYZ_DEMAXIN
Hey guys I just bought me an 04.5 GMC Duramax/Allison. My old truck was an 01 Cummins that had several mods done to it. I loved it and know all about cummins and how to soup them up, but I have always been a die hard Chevy guy. I finally got me a duramax and I was wondering what are the tricks to make these duramaxes run.

Im wanting to know what are the little things I can do to them to make them run better. What is the best chip/programmer, what to do to help the tranny and rest of the driveline hold up better, and pretty much the most common best mods to do to them.

I don't know much about these duramaxes at all, they are all new to me. But i plan on being on here alot to learn all i can about my truck. I used to be on DTR all the time when I had my cummins and I learned a whole lot about the Dodge/Cummins pickups.

Thanks for all the help,

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Welcome to the DF!!

How much extra hp do you want, its easy to make well over 400RWHP but your biggest expense will be the trans upgrades but you can usually get low to mid 300'sRWHP on a stock trans!

I would start with Gauges ( pyro and Boost) then a 4"exhaust with Cat deleat front pipe, EGR_BLOCKER_AND_CODE_BLOCKER ( to deal with engine codes from the exhaust) ANd then a programer Diablo Predator being my #1 choice because it adds some extra boost on the lly's and you will not need a finger stick using a predator because it has a egr off function in it!! But if you want the biggest power go with PPE_HOT_ET+2 but you will need trany upgrades with it on the high settings!!!

Hope this helps,
Thanks for the reply. I also have a few more questions if you don't mind.
I was looking at different exhaust systems to go with and I ain't real sure what sounds the best on these duramaxes. I know that on a cummins, 5" sounds way better than 4". Is that so with the duramax also? What does an lly sound like without a cat or muffler? I have heard the lb7's straight piped but I haven't heard a lly with the variable vane turbo straight piped yet. Will it sound better with 5", or should I go with 4"? Or should I just leave the stock size and just have the cat and muffler cut off? How would this sound?

Also, I see that alot of you guys are using the EFI live for tuning, is that better than just using a programmer? What all does the EFI live do and how do I go about getting it?

Thanks for all the help, I know there is alot of questions, but I don't know who else would know besides yall.

You guys sure are alot of help.:rant
EFi live is by far the best tuneing for the dmax but it is a time consun=ming custom tuning software. It is not just a plug and play tuner. For efi try one of these two places they are by far the best in customer support and tuning support! Pat @ and Guy @ either one of these guys offer a great starter tune with efilive!!

For a good exhaust i recomend Mbrp 4" the 5" offers no more than looks to a lly IMO! Lots of supporting vendors here sell them try Pat or Larry @
My brother is on DTR (2001 Dodge Cummins) all the time and I have lurked there before and I see there is a whole bunch of information that is exchanged on that forum. There has got to be a few more Chev/GMC experts on this forum that can pitch in with valuable info?.?.?.

I am very interested in finding what simple mods I can do as well as what issues to keep an eye on with my 03 Duramax.

i love my ppe hot e.t.2 but like 05 LLY said i the highest setting a tranny upgrade is a must in my truck i have bully dog shift kit and it really helped but i'm looking to put a after market tranny in it because the shift kit wasn't enough.if you want the best go with efi live there is none i love my 5" exhaust:rockin
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