Anyone know where I could get a downpipe that for the LLY without the cat in it?
Thanks
DAN

you can check with a dealer for one of the lb7 01-03. Or you can get one from several of the manufacturers, exhaust, websites. You can search here for a few threads that will show you some links.

Supporting vendors sell them...I picked up one last week

dwrat,

We have them comming out of our ears, we can send you one any time!!

Mark @ DPPI

A 4 inch pipe out your ears? Sound painfull...

MBRP MAKES A GREAT TURBO DOWN PIPE THATS BOLTS INTO THE STOCK EXH SYSTEM! PART #GMS9401 STAINLLESS STEEL AND LARGE DIAMETER! ALSO FITS WITH MBRP SINGLE OR COOL DUAL EXH SYSTEM. FITS LIKE A GLOVE-EASY INSTALL! BUBBA:cool2:

Not to get too technical, but its actually the Front-pipe you are looking for. This pipe will replace the Cat on 04.5+ LLY trucks. This pipe will bolt up to the down pipe and has the 4-bolt flange in the stock location so it is a direct replacement for the factory front-pipe.

He is correct..the "real" downpipe is probably never going to have an aftermarket replacement. Its in such a tight spot and shaped so flat to fit next to the fire wall.

This LB7 front pipe.. if you use your stock muffler and pipes will you get EGR codes???

I had installed a complete system a while back, front pipe to tip, and got EGR codes and truck ran like crap, smoked, smell of fuel...blah blah..

I have heard that if you keep either the cat or the muffler you will have enough back pressure for no EGR codes..

anyone know if this is accurate?

I'm running an lb7 front pipe and stock muffler, but can't check for codes yet. Buy me a predator and I'll check... No check engine light though, but that doesn't mean it doesn't have codes stored.

I'm running an lb7 front pipe and stock muffler, but can't check for codes yet. Buy me a predator and I'll check... No check engine light though, but that doesn't mean it doesn't have codes stored.
autozone will do it free

Yeah but who wants to drive 160 mile round trip to cheyenne to go to autozone? Actually I could probably get the guy at the dealer to do it for free, it just hasn't been bothering me. I don't think it set codes the way it is anyway. Now when I try straight piping it then it might. But I doubt it.

thats too funny...I was actually born in Cheyenne LOL

really? Cool.. I was born here in wheatland, not planning to leave.

Has replacing the LLY downpipe with the LB7 helped lower EGTs? If so how much?

kbk-look at "no code exhaust" topic. rickdlance said he has noticed lower temps. I wouldn't know on mine,I don't have a pyro.

I gave up fighting it today and ordered a "code reader".;) Hopefully be here by thursday, when it gets here I'll check and see if I have any codes from the exhaust. I bet I don't though. 3.5 inch pipe is 3 something a foot at napa, so I might get some and straight pipe it this weekend for fun too. I have the entire pipe from the lb7 so I can straight pipe that tailpipe and keep mine whole and put it back on if I want. Can't wait for my "code reader" to get here so I can read my codes... And add some power...:ro)

I just installed the MBRP pipe...EASY! I'm also using the egr blocker plate and have no codes listed by OBDII reader.

I just installed the MBRP pipe...EASY!I just received this pipe yesterday and have yet to install it. One end has a flange, the other is "different."

I haven't looked at it closely, but how does the Turbo end work???

If everything goes well today, I'll be under the truck tonight!

-Jeff

I haven't looked at it closely, but how does the Turbo end work???

-Jeffyou will use the band clamp that is currently holding your stock front pipe to the turbo down pipe. just transfer it to the new pipe. it wraps around the lips and secures it. this is easiest when the rear portion of the pipe is supported or loosely connected. doing it with one arm while trying to center the clamp is a pain in the butt.

OH and I forgot to mention..in order to get the stock cat pipe out you will have to remove the bracket on the tranny that the pipe uses as a hanger. Once that is removed the stock pipe will slide out the front.

nar, I hope you ordered a diesel specific code scanner. Some of them won't pick up all the Duramax codes. Also, for the record, my EGT's are amazingly low with the "no-cat', "no-muffler", "no-code" exhaust. Tested the gauge several differant ways. Have ordered 1 of those infa-red thermometers to try to test for sure.

MBRP MAKES A GREAT TURBO DOWN PIPE THATS BOLTS INTO THE STOCK EXH SYSTEM! PART #GMS9401 STAINLLESS STEEL AND LARGE DIAMETER! ALSO FITS WITH MBRP SINGLE OR COOL DUAL EXH SYSTEM. FITS LIKE A GLOVE-EASY INSTALL! BUBBA:cool2:

hold off on purchasing this part number...I am on the phone with DPPI right now and they are telling me that it will NOT bolt up to the stock pipes becaues of the diameter difference.

MBRP MAKES A GREAT TURBO DOWN PIPE THATS BOLTS INTO THE STOCK EXH SYSTEM! PART #GMS9401 STAINLLESS STEEL AND LARGE DIAMETER! ALSO FITS WITH MBRP SINGLE OR COOL DUAL EXH SYSTEM. FITS LIKE A GLOVE-EASY INSTALL! BUBBA:cool2:

Bubba, are you positive about this part number and application??? DPPI is telling me that it will NOT fit on the stock pipes.

CORRECTION... GMS9401 WILL fit the stock flange and MBRP flange.. the guy just called me back after talking to Mark.

nar, I hope you ordered a diesel specific code scanner. Some of them won't pick up all the Duramax codes. Also, for the record, my EGT's are amazingly low with the "no-cat', "no-muffler", "no-code" exhaust. Tested the gauge several differant ways. Have ordered 1 of those infa-red thermometers to try to test for sure.
Oh yeah, I know my "code reader" will work with my diesel. It's the same one you have. In fact your reviews of it helped me decide to buy it. Notice the "" ;) I was just playing sneaky... Good to know that your EGTs are way low, because I don't have a pyro, and I'll probably change my exhaust more. Probably a mufflerectomy. What elevation are you at? I'm over 5000 feet, I have seen people posting that they had higher temps up here than lower.

I am only at 900 feet here, but I am heading for Tucson tommorow. Should get up just over 6200 feet on the way. I will try to keep you informed. I did check my gauge with the boiling water test and it showed correct temp. Are you happy with the "code reader". I would hate to steer anybody wrong. Where in Wyoming are you. My wife has a delivery in Casper Saturday and my sister-in-law used to live in Rawlins.

I should get it tomorrow. Then I'll check for codes... Among other things... I'm in wheatland, you go through it all the time on I-25 I bet.

i received my downpipe and it is a 4". My question happens to be in regards to the rest of the exhaust being the stock 3.5". WIll I have any issues? I originally wanted to remain stock the rest of the way but I think I may have to go 4" all the way from the turbo back.

If so, has anyone heard of the twister muffler and have any experience with it. I have a local custom shop that will fabricate any exhaust of any size for me. I will look at the costs of it.

maybe i shoudl have read briano's post before this. I guess it answers my question.

Got my "code reader" today. No codes stored in my truck from running with lb7 front pipe. I had also run it briefly with nothing after that to see what it sounds like. So there probably would have been codes from that too I would think, but there was nothing. I may do the mufflerectomy this weekend, depends on weather/time. Then we'll see what it says.

Oh and my truck feels about 65 hp stronger too. Handy thing this "code reader". Seems my speed limiter is gone as well, huh....:cool2:

FWIW, If the intake air temp is below 32*, the ECM will not run the EGR test and not set codes. I see some of you are in cold climates and not getting codes. Check again after a warm day.

Ok, I'll bite. What is the single largest advantage to removing the cat and replacing the downpipe on the LLY engines?

lower EGT's is the biggest, but mileage is up there! Those are the two I am concerned about.

Thanks Brian. On those two issues, what is the practical difference you are seeing? EGT's goes sort of without saying, but what about MPG's? 2 mpg? 3?