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Discussion Starter #1
For those of you newbies/veterans wondering if it will fit or what it looks like or whatever, here you go. I ordered this frontpipe from Mark Craig at DPPI (http://www.dieselperformanceparts.com) and the part number is GMS9401 and is an MBRP product. It arrived 2 days after I ordered it. As you can see from the pics the flanges do in fact line up just fine and just retain the gasket that came on the stock pipe as well as retain the band clamp at the turbo down pipe side.

The ONLY thing you will need to do to remove the stock pipe is remove the 2 bolts holding the hanger and bracket onto the side of the tranny. There is one clamp on the turbo side with one nut, you will reuse this. There are 4 bolts on the rear. Once that is removed you can slide the entire stock cat pipe out the front with no problem at all. This works for 2wd adn 4wd. You don't need to remove crossmembers on either.

In gear at idle with the stock pipe my EGT's were 400+..since the EGR is active only at idle and highway speeds I sat in the truck with it in gear for 15 minutes. The temp never got above 342, so that is an immediate 50+ degree drop just at idle.


 

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Nice. Good to know it did lower EGTs.
 

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I'll be there soon!

Thanks briano! :grd: I am going to be out of town this week, so I will probably be doing this next week. Thanks for all the info and your help last week! I too am seeing EGT's at about 400 at idle in gear, I can get down to 325 or so in park/neutral, but my worry was this summer when I start pulling my 5er. Do you know how much they have reduced temps during 'normal' driving? Have you seen -200 deg like I've read in other posts?
 

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Good job Brian. Do you have the drone noise that we have been talking about on this thread HERE ? If so, did changing the pipe change the noise at all?

Also, how long did it take you to do the conversion? Did you have any trouble getting to the flange bolts / band clamp up by the turbo side?
 

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Discussion Starter #6 (Edited)
Throwing codes...from what I have learned and been told, as long as there is some sort of back pressure the EGR should be ok. I will find out for sure though and let you know. I retained the stock muffler so that should be enough.

I will also find out today about normal temps driving around. I have been monitoring them for a while so with this pipe installed I'll be able to tell if there is in fact a drop.

Time it took... the entire process including washing hands twice, getting camera, removing cat pipe, installing LB7 pipe...less than an hour. No problems removing any flange bolts or band clamp at all. Its a very easy install. Reinstalling the band clamp on the turbo side can be difficult if the rear of the pipe is not supported. either on the hanger or losely put a couple bolts on the rear flange.

Drone... I am not sure if I ever heard this drone noise before. I hear the normal workings of the motor and exhaust, but never really considered it to be droning at all. maybe I am one of the lucky ones.

I have to travel to San Antonio today to get my car so I will be doing highway and then some towing so I'll let you all know what temps I see and I also am bringing my OBDII scanner along with me and check for stored codes whenever I park.
 

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Very nice write-up on the front pipe installation, I just installed one yesterday and the installation went equally as well. I purchased my pipe from performancetruckproducts.com, who I believe is a site sponsor. I like to say that the quality of the pipe and fit were outstanding. If anybody is interested I own a 2004.5 and luckily haven’t had any of the issues that I have read about on this form except the raw fuel smell at idle. The dealer re-flashed the computer with the latest updates, it did quiet it down at idle and smooth out the power delivery during normal driving. This is just seat of the pants tuning, but I was disappointed in the re-flash because I felt a flat spot whenever I accelerated moderately, when tipping the peddle slightly, the truck just wasn’t as responsive and I still had the smell of raw fuel at idle. I’m posting this message to say that after installing the new front pipe I don’t have that raw fuel smell and the truck really came alive. No more flat spot and the truck runs and accelerates cleanly. I didn’t detect any difference in the noise level. The finger stick and EGR plate are next. This form has been very informative, Thanks
 

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Can you install the downpipe with an aftermarket exhaust and not install the fingers or EGR plate? Will this throw codes?
 

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Discussion Starter #9
I have already swapped out my entire exhaust a few months ago and yes it did throw codes, its basically a straight through system, no restriction. I did not have fingers or egr plate.

I talk to Mark at DPPI and he said as long as there is some restriction it should be fine. I just kept the stock muffler. So far the sound has not changed and the temps actually don't seem as low as I had originally thought, but still are about 20 degrees cooler.

I'll know more after my trip today.
 

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i did mine and the hardest part was taking out the old pipe. i do have the fingers stick and egr blocker plate as well. it is just for the added bonus of cleaner oil longer and clearing any possible codes if I go all the way with the exhaust.

I know if anyone wants to try this, i used a 7/16 ratcheting boxend wrench for the clamp. Mine is short so it worked real well in the tight spot.
 

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Thanks for the Info Briano, Looking forward to your update from San Antonio..!!
 

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Discussion Starter #13 (Edited)
Well, back from towing my car up from San Antonio. I have gone about 200 miles today half of it with empty trailer, other full. I used tow mode the whole time along with Edge on level 2. I watched the temps the entire way and the only time they spiked was going up hill where the load is greater. The highest it went was 1034. Empty is about 1800lbs and full is almost 5000lbs.

I am not sure about mileage at this point, but from the looks of my guage I got ok mileage. the truck seems just a bit smoother on acceleration, EGT's seem just a bit lower..not much. Other than the more audible turbo whistle I can't really see any difference. I am hoping the city mileage increases.

Not sure exactly if this is what ya'll wanted to hear, but that's it. I guess I was hoping for more, but we'll see.

OH..and so far no codes, but its only been one day. I checked the codes before I left and when I got there.
 

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Keeping my fingers crossed. Thanks for the update.
 

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By chance did your front pipe come with a new 4 bolt flange gasket? Is there any gasket on the other end?
DAN
 

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Discussion Starter #16
dwrat said:
By chance did your front pipe come with a new 4 bolt flange gasket? Is there any gasket on the other end?
DAN
it does not come with a new gasket as you can use the stock gasket on the 4 bolt flange. there is no gasket on the other end, only a band clamp that is also reused from stock.
 

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I'm kinda new but....

Is the Lb7 pipe an aftermarket pipe that also works on the LLY engines? This isn't the old stock pipe that GM changed on the new engines correct?
 

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Discussion Starter #18
Is the Lb7 pipe an aftermarket pipe that also works on the LLY engines? This isn't the old stock pipe that GM changed on the new engines correct?
if you look in the very first post I have the Brand, part number and who I ordered it from. its a 4" pipe, no left over stock LB7 one.

"I ordered this frontpipe from Mark Craig at DPPI and the part number is GMS9401 and is an MBRP product."
 

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I read that part...it was more of a curiosity question as to if it was an aftermarket part bar none or similar to the LB7 stocker. I've never owned a diesel before and this will be my first one.
 

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Discussion Starter #20
I read that part...it was more of a curiosity question as to if it was an aftermarket part bar none or similar to the LB7 stocker. I've never owned a diesel before and this will be my first one.
oh ok..usually most never read the entire thread.. lol

yes its an aftermarket pipe, 4" and fits LB7 and LLY, its stainless and bolts to the stock 4 bolt flange or to an aftermarket 4 bolt flange.

the stock pipe is 3 or 3.5" in diameter not to mention is much lighter without the cat on it.

hope this helps.
 
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