Diesel Place banner

1 - 10 of 10 Posts

Administrator Mister, your truck's smoking...
11,398 Posts
Many thanks to rader2146 for this sticky. A couple of points. First, this sticky is still under development; if you have suggestions, contact a staff member via PM and we'll work to integrate your comments into this sticky. Second, in the Q&A section of this sticky, where there are multiple answers to the question, they are all listed. The reader should take care to understand what's behind the multiple answers.

The LBZ/Kodiak Mouthpiece upgrade is one of the most talked about and debated subjects for the LLY. This post is an effort to consolidate the information and give a general understanding of why and how to do this modification.[/color][/size]

The stock LLY mouthpiece is a known "weak link" in the air induction system. It is under sized and restrictive to such a degree that it causes turbulence directly in front of the turbo impeller. Turbulent flow = loss of efficiency. This loss of efficiency is at it's worst during high load situations that require a large amount of airflow to the turbo. The problem is compounded even further when increased performance is desired via a tuner/programmer. Adding boost pressure over stock requires more airflow through the mouthpiece, which makes the effect of the turbulence greater, causing it to impact efficiency even more.
Replacing the mouthpiece with a larger and less restrictive version will correct this shortcoming, giving you back the lost efficiency of your turbo.

AFE has released its version or the turbo mouthpiece. It is intended to be a direct replacement for the stock mouthpiece. Product details and discussion can be found here.

Q: What is a turbo Mouthpiece (aka “MP”)?
A: The pictures are worth a thousand words.

Side By Side comparison:

Notice the sharp angle on the stock LLY MP:

And the smooth bend of the LBZ MP:

Side by Side - LLY vs LBZ:

The difference is clear. The LBZ MP and Kodiak MP are larger and will flow better than the stock LLY MP.

Q: Is this upgrade a direct swap?
A: NO. However, it can be done with a few simple hand tools.

The LBZ MP is longer and requires a larger diameter coupling to adapt to the stock LLY intake tube.

LLY vs LBZ intake couplings:

Also you will need to cut you stock intake tube to account for the additional length of the LBZ MP. The measurement for the cut is 2" - 2.5" from the yellow caution sticker. Hint: To make a straight/square cut put a hose clamp on the tube at the cut line. Tighten, and use it as a guide to make the cut.

You will need a 4" ID coupling. You can source the coupling from many different places. Your local hardware store or home improvement store will have a "Fernco" coupling that can be found in the plumbing section. For higher temperature protection a silicone coupling can be used. Most Auto parts stores will have "Spectre" silicone couplings. If they are not in stock, they can order them for you. Summit Racing and Jegs are also popular sources for silicone couplings. Google will also turn up thousands of different silicone coupling vendors. Look for performance automotive shops that specialize in turbo applications.

An LBZ MP Installation kit can be purchased here. = Custom Intake Tube, Couplings and clamps.

An LBZ MP "How To" installation can be found here.

The Kodiak MP is slightly different than the LBZ MP. It does not have provisions for the Resonator (Black "6.6 TURBO DIESEL" thingy on top of motor.) It also has a slightly smaller inlet that is the same size as the stock LLY Intake tube. No cutting is required for the installation of the Kodiak MP. The upside of this is that, if needed, you can easily return back to stock form. The down side is that your intake tube will be slightly elevated and the accordion coupling will be slightly canted.

You can also cut the stock intake for a cleaner appearance. For this you will need a 4" to 3.5" reducer.

Q: Where can I get a LBZ or Kodiak MP?
A: www.gmpartsdirect.com

Q: What are the Part Numbers for the LBZ and Kodiak MP?
A: LBZ - 98011738 (This PN was said to be discontinued. As of 9-13-09 GMPartsDirect says "Currently in stock and ready for prompt shipment.")
A: Alternate LBZ PN (Actually an LMM MP PN, but they are the same part, with a different price.:() - 98003367
A: Kodiak - 98011736

Q: Will the LBZ MP or Kodiak MP work with my LLY aftermarket intake?
A: Most intakes can be retrofitted to work with either MP. You have to be willing to cut the excess length off of you aftermarket intake tube. Also make sure and measure the diameter of the intake tube where you will need to cut it. Some aftermarket intakes have a different diameter than the stock tube so a 4" ID coupling might not work for you.

LBZ MP with LLY S&B Intake:

Q: I do NOT want to cut my intake tube. What options do I have?
A: 4 options.
1. Get the Kodiak MP. As stated above, the accordion coupling will be slightly canted.
2. Get the LBZ MP and an aftermarket LBZ intake. They will match up very little to no problem at all. This is a very popular option.
3. Get a stock LBZ Intake and MP. Make sure to get all the seals and baffles that go with it. Read below for more information on the stock LBZ intake system.
4. AFE's Turbo MP is supposed to be a direct swap. No cutting involved

LBZ MP with Banks LBZ Intake:

Q: Can I get a Stock LBZ Intake for free or little cost (warranty deductible)?
A: Yes. GM's "solution" to the overheating problem is to replace your stock intake system with a modified LBZ intake system. You MUST be under the 5yr/100,000 mile warranty, and must convince your dealer that you have an over-heater. It seems to be very difficult to get the the dealer to do this. See the TSB attached below for more details. Note: THE TSB DOES NOT REPLACE YOUR LLY MP WITH THE LBZ MP. YOU WILL HAVE TO ACQUIRE AND REPLACE THE MP YOURSELF.

Q: Do I have to get my ECM (Engine Control Module) "re-flashed" when I upgrade the MP.
A: Only if you use an Intake system designed for the LBZ. If you use the stock LLY intake or an after market LLY intake you will not require any ECM modification.
If you use an LBZ intake, stock or aftermarket, you will need to have the ECM re-flashed to adjust the MAF (Mass Air Flow) sensor. Refer to Step 24 in the TSB below for more information.
The ECM can also be re-flashed with EFI Live using the corresponding LBZ MAF table.

Q: I had my ECM re-flashed. Can I still use my Programmer/Tuner/Box?
A: Yes. There have been no known issues after the re-flash.

Q: Will this upgrade cure my overheating?
A1: Without a doubt, NO. The overheating issue runs much deeper than this upgrade. Check the other LLY "Sticky's" for the solution.
A2: It may help a little... in that EGT's are reduced.

The Mother of all questions: How much horsepower will I gain from this upgrade?
A1: Dyno Results

This is NOT a "performance" upgrade. It is aimed at increasing the drive-ability of the truck and reliability of the turbo by correcting the turbulent flow. Doing this results in decreased EGT's and reduced turbo shaft rpm.

Common reports of the upgrade are:

- 100*F reduction in EGT's. Some reports of over 200*F reduction
- Faster spool up, aka reduced turbo lag.
- .5 - 2.0 MPG increase. Empty OR Towing.
- SOTP (Seat Of The Pants) meter says the truck is faster. If your truck is pushing 500 HP before the upgrade then this is more that likely true. There are track results that support this for high HP trucks. For trucks less than 500 HP, looking at the dyno results, this can probably be chalked up to placebo effect. But it's not always about what's on paper, it's what makes you feel good.:D;)

A2: This IS a "performance" upgrade. As you approach 500 RWHP (or more), this modification has been shown to add as much as 35 RWHP. Have any doubts? Check out any high performance diesel sled puller or drag truck; NONE of them are running stock intakes - they are ALL running large turbo mouthpieces and large induction systems - more air equals more power.

Q: Is there POTENTIAL for higher horsepower with this upgrade?
A: ABSOLUTLY. I mentioned track results above. In the case that you push the stock MP to it's limit(~500hp, but that is speculation based upon an educated guess, and the track results mentioned above), this upgrade is for you. By correcting the the restrictions and efficiency loss you push the stock turbo's max boost rating from ~32psig @ sea level to ~36psig @ sea level.

If you have questions that have not been answered or would like to share you experience with this upgrade, PLEASE do not start a new thread. Come join the discussion in the thread below. Also, please give the search feature a chance. When you see the size of the thread below you will understand that there are just too many questions to cover in one post.

MP Discussion thread: Seen this yet II

I cannot take credit for any of the information or pictures in this post. Thank you to everyone that contributed to this upgrade. Without great minds that are willing to experiment, we would be stuck with that 5 letter word that everyone hates....STOCK...


LLY to LBZ Mouth Piece DIY Install

It has been discussed that the LLY Turbo Inlet Duct (or commonly called the Mouth Piece, from this point forward called ''MP'' or ''Mouth Piece''), is very restrictive at the 90° bend. Some have removed this piece and have deburred, Dremelled, ported or ''smoothed out'' (whatever you want to call it), the sharp edges for a slightly better flow to the turbo. Somewhere along the line, someone discovered that the LBZ MP (mouth piece) was a direct fit and would clamp on in place of the restrictive LLY MP. GM knew this and switched the design to the current configuration (where’s the factory recall?). With this extra available air, LLY owners were finding slightly cooler engine coolant temperatures and slightly better mileage. With that said, you are probably seriously considering this modification now.

Typically, people are ordering the 2006 LBZ MP (part #98011738). The LMM MP will also work (please refer to the parts listings above this segment). The LBZ / LMM MP is what I'll be discussing about installing. Dealer retail is around $126. plus shipping and people have reported being able to order it from part sources on the internet in the $67. to $86. range plus shipping. The LBZ MP has provisions for the PCV and Resonator box. People have also been ordering the MP for the larger trucks (Top Kick and Kodiak). These DO NOT have the Resonator box provision (nipple) so it's your choice. The Kodiak/Top Kick part #98011736. The LBZ outer diameter measures approximately 4.2", while the Kodiak is the same as the stock LLY at approx. 3.85" outside diameter at the tube clamp. Keep in mind, the Kodiak/Topkick MP has the large opening where it mates up to the turbo, thus is also an improvement over the LLY.

In the discussion below, We will be installing the Mouth Piece only. You will keep your existing LLY Air Filter Box and tube leading to the Mouth Piece.

Here is what your LLY MP looks like removed. Note the sharp edges on the inside 90° bend.

Here is the LBZ MP...

The outer diameters are the same where they mate up with the turbo, so they are interchangeable...

Here are the LBZ, Kodiak and LLY for comparison (thanks for the pictures wilsonck)

Now for the install of the LBZ Mouth Piece. First remove your Resonator box by loosening the clamp and popping off the front mount.

Next, remove the PCV hose clamp and hose...

Now, locate and loosen the V-Band clamp that holds the MP to the turbo.

Loosen the tube clamps at the Stock mouth piece and where it connects to the filter box. Lay this tube to the side.

At this point, remove your stock LLY MP. You will have to pull and tug GENTLY on your wire harness to get the required new room for the larger LBZ MP. There is a bracket you will remove to gain the required room...

Next, you will be cutting your stock LLY tube shorter for the increased length of the LBZ MP. I found 2 1/2'' from the label to be good. You may want to cut it at 2 1/4''. Sand or file off the rough edges and be sure to wipe out any debris that may be left in the tube...

Now install your LBZ (or LMM) Mouth Piece. Tighten the V-band clamp (Turbo to Mouth Piece clamp).

You may run into a clearance issue as I did. The EGR pipe has a 5/8’’ coolant tube that sometimes interferes with the LBZ Mouth Piece when trying to bring it down to it’s proper position as the locating tabs dictate. There are three thoughts on this. 1) Grind on the lower rib of the Mouth Piece for clearance. 2) Cut the location tabs off and bring it down as close as possible. 3) Bend the coolant tube in to gain the clearance needed.

Next reinstall the PCV hose and Resonator box then and retighten the clamp. Pop the resonator box grommet back down on it’s mounting peg. You may want to block off the resonator port and do the PCV reroute modification at this time (second photo).

Next, reinstall this modified tube. Use your original clamp at the air filter box. I used a 4'' by 4'' rubber pipe connector found at Lowes hardware stores ($6.95) and just butted up the cut LLY tube to the LBZ MP and tightened the clamps. This was temporary, You will want to go with a coupler made for Turbo applications. I installed the entire LBZ CAI, but that's another story.

Double check your work and you are done!

The beauty of this modification is you get increased airflow without having to recalibrate your factory MAF (mass air flow) sensor. If you decide to buy the entire LBZ (or LMM) setup, you will need your ECM flashed by the dealer.

Thanks for the additional photos and input rader2146, RoadRunnerTR21, Randy_the_hack and wilsonck. DDD

41 Posts
Great Job on the sticky. Thank you.

Administrator Mister, your truck's smoking...
11,398 Posts
Discussion Starter #3
As stated above, the credit for the sticky goes to rader2146.

Ride, shoot straight, and speak the truth.
4,279 Posts
Here is the TSB for the '06 Intake.


3,563 Posts
Good write up Pat! This should help a lot of people out there wishing to do this.

That's the cool part about this site... People willing to share information. We simply passed on the information that was passed to us.

2,226 Posts
Great information....I tried to get the dealer to replace my MP. Gave up and installed the LBZ MP myself. Very easy and affordable....

6 Posts
Many thanks for this information. Nicely put together and presented.
Makes me want to order parts pronto. I would do it for the improved towing fuel mileage.

1,486 Posts
I checked at the GM dealer today for the LBZ mouthpiece, and they are no longer available. The kodiak one is still available but it was going to run me 250 bucks. Keep in mind that is in canadian and we get ripped off big time for parts in central alberta.

Administrator Mister, your truck's smoking...
11,398 Posts
Discussion Starter #9

94 Posts
If I wanted to buy the full LBZ intake, what part numbers would I need?

Or would it be easier to buy an aftermarket LBZ intake for my LLY?
1 - 10 of 10 Posts