Has anyone tried to just remove the muffler on the LLY and leave the cat? If so what does it sound like?

While installing my MBRP cat back exhaust I fired up the engine with the orignal exhaust removed along with muffler. With the cat only on the truck the sound was just barely louder then with the whole system on. With the MBRP system installed it was about the same in sound. Did not run the truck with the system off so can't say how loud it might have been in the cab at running speed. No noticable dron in cab after instalation. Very pleased with system now.

I did this last week just to see if i could hear more turbo whistle and it was more annoying then anything to be honest real bad drown sound in the cab........I guess if I were to completely remove the cat then maybe I would hear more whistle.............time to order a mbrp system. I also used a hole saw to open up the air box and I can hear a little more noise...........it maybe only took me about 10 mins to remove the exhaust from the cat....undo 4 nuts and your good to go....i spent more time tryin to remove those rubber exhaust hangers then anything.......gotta remove the 2 hangers to drop the pipe

Spray a little WD-40 right onto the rubber where it goes over the metal hanger........twist a little back and forth and it will pop right off.





Thttp://www.dieselplace.com/forum/smileys/Clown.gifNY

does removing the CAT, set off any codes? and how easy or difficult would it be to put the CAT back on come inspection time? Plus with that CAT gone, does it run any better? or how does it sound?


Id like to order a system here soon for my LLY but just kinda having trouble finding consistant info about whats what....so any help would be great!http://www.dieselplace.com/forum/smileys/Geek.gif


thanks!


Jared

Removing the cat will set codes. I removed mine day one and the check engine light never came on, but there were codes set. P0401 and P0404 I believe. Both EGR related.


The system sounds good with or without it. I am going back and forth with it right now trying to feel the difference. It is easy to switch out with the MBRP system. Hope this helps. Let me know if I can help with anything.

DSTRBD does it effect the engine in the long run?


Do you have the muffler on or do you have the delete pipe installed? if so whats the sound diffrence between them?


Thanks

Good question. No one seems to know.


I have the MBRP muffler. Sounds great with it, not sure without it.

Will the exhaust temps be higher having the cat on there or does it not really restrict the exhaust flow. I'd like to put a 4 inch system on mine plus some sort of chip or tuner, don't know which one yet though. I was just wondering if the exhaust temps will be higher if I leave the cat on. Don't wanna burn that turbo up ya know.http://www.dieselplace.com/forum/smileys/Approve.gif


Thanks

Whats the install on the MBRP system like? is it somthing that can be done with basic hand tools and a good socket&wrench set? also can it be done on the ground? without having a lift? ill be ordering soon, so any suggestions as to where to buy are helpful!


thanks


Jared

My install was done on the ground with just a socket set. The longest part was cuting off the old system with a porta-band. You will need some WD40 for the rubber hangers to slip off then on. Whole process took about 45 mins. Used the box it came in to lay on, everything you need is supplied, even the ground coverhttp://www.dieselplace.com/forum/smileys/Big Smile.gif


Paul

Whats the install on the MBRP system like? is it somthing that can be done with basic hand tools and a good socket&wrench set? also can it be done on the ground? without having a lift? ill be ordering soon, so any suggestions as to where to buy are helpful!


thanks


Jared





Although mine is a LB7...........


I just used a floor jack to get my truck tires on cement blocks, then all I needed to do was remove the right rear shock to make it easier.





http://dieselplace.com/forum/uploads/AB4_Dual_rear_view.jpg








Thttp://www.dieselplace.com/forum/smileys/Clown.gifNYEdited by: GMC-2002-Dmax

Very easy and straight forward install. WD-40, socket set, sawzall m(optional), and your ready to roll.


1. Give the hangers and rusty bolts a good shot of WD-40 a few minutes before you start.


2. Remove the 4 nuts from the 4 bolt flange.


3. Decide if you are going to try and salvage the stock system. If so, you will need to jack up the frame on the rear end to get the stock pipe over the axle. If not, cut away.


4. Remove clamp from stock front-pipe. (if you ordered new one)


5. Once the system is completely removed, start with the new fron-pipe. Secure this piece in place before any others.


6. Loosely fit the rest of the system in per directions included.


7. Once everything fits like it should and has the proper clearance, tighten up all the clamps.


Please allow 5 minutes between each step for proper lubrication of your choice, I prefer Mich Golden Lighthttp://www.dieselplace.com/forum/smileys/HiHi.gif


If you have any questions, let me know.


Edited by: DSTRBD

I would be extremely interested to know if anyone has tested their systems on a dyno with the muffler in place and with the muffler delete pipe installed. Seems like a big selling point for some of these systems is that the muffler has a spiral pattern inside, promoting the same airflow patterns exiting the turbo. Does this really make a difference? If it does, then running straight pipes could actually result in less power than running a muffler.


Thanks,
Dennis

baimpala,


In all the testing I have done and seen the Spiral Flow muffler gets you the exact or slightly better flow than a straight pipe. Now rememebr there is very little way to measure this without spending approx $10,000.00 to get the last little bit of data, but on a basic flow bench there was a slight advantage in the Spiral Flow over a straight pipe. Hope this helps you.


Mark @ DPPI

What about the CAT?, nobody seems to know how much it does or does not restrict. I was thinking of getting MBRP system and the down pipe and removing the CAT, if it gives me problems then I can bolt the CAT back. That CAT on the LLY is huge, it has to be holding something back!

yeah,


What redneck 45 said. what's the deal with the cat? Will the truck run fine if it's removed? Will it void my warranty? Will it cause higher exhaust temps when I put a power program on the truck. Will it or will it not be ok to leave it on?

Is there any real advantage to having stainless vs. aluminized? besides simply having a stainless exhaust?





DSTRBD....im a bit under age to stop between steps, so that makes it harder to come by, so i believe ill just keeep on a workin....http://www.dieselplace.com/forum/smileys/HiHi.gif


im also interested in the CAT, weather or not it helps or hurts?


Thanks


Jared

anybody? what's the deal with the cat? Better on or off? Negative and positive effects.

Morning,


The current cat is a high flow design, it's light years better than those in previous years for sure. Yet it is still a restriction, just not as bad as before. You will see an average of 10% better EGT's with it out and a little better spool up etc etc. There are a lot of variables in this 10% based on atitiude, towing weights or empty, brand of module used or stock etc. You will also get some extra exhaust sound, some folks leave the cat in to eliminate the sound, other want it out just to get the sound and don't care about the egt reductions etc. To each his own for their own reasons etc. The big advantage of an MBRP system for you guys is the front pipe is available as a seperate optional part, it bolts in at the 4 bolt flange and V band clamp so putting it in and out is pretty painless. remember you need to be doing off road and or racing to be legal without a cat in a factory cat equipped vehicle. The dealerships get a little testy too on a cat-ectomy, so watch what you do as far as warranty.


Staniless vs aluminized:


Well the aluminized is slightly less money, but for approx 40.00 or less you can get 409 stainless, well worth it to me as the factory system is stainless. Plus with all of our stainless you get all the welded hangers made out of 304 stainless to make sure they never corrode at all. Aluminized system don't get those etc.


The systems are available in aluminized, T-409 and T-304 stainless steel. The duals are available in Stainless only. Let me kwon if you have any questions etc.


Mark @ DPPI

anybody? what's the deal with the cat? Better on or off? Negative and positive effects.


You need to send a PM to McRat. He has run with and without the cat on a LLY equipped vehicle. He has posted somewhere on the board about it but I couldn't find the post quickly. IIRC he got EGR codes with it removed and did not notice any seat of the pants improvement. Get ahold of him to get the answers.

thank you for the info diesel tech and mark craig. That answers my questions. I'll drop a PM to McRat to get his input on this too.


thanks for the advice it is greatly appreciated. http://www.dieselplace.com/forum/smileys/Approve.gif

This is my 1st Duramax, so what I need to understand is, is this MBRP a turbo-back system or from the downpipe back system? Edited by: coolbeans

MBRP is DP back.


I have been doing some testing with the Cat converter this past week. To tell you the truth, seat of the pants there is no difference with it on or off. The only difference is Tech II no longer shows the 2 EGR codes. I have not had time to drill and tap for a pyro to see if there is an EGT difference. I assume that they will be higher, but not much. I know I will be leaving it off to get maximum flow because these trucks naturally run hot. Edge has confirmed over 1400 deg. stock while towing up a grade. Kinda scary.

http://www.dieselplace.com/forum/smileys/Shocked.gif 1400 degrees!! Jeezzzz & looweezzzz!!


I'll have 1000 non-towing miles on 'er pretty quick, maybe that helped it lube up a little better b4 I put my trailer behind it. I can see now that if I put nothing else on it, exhaust is going to help out some.

coolbeans,


The standard system bolts on from the 4 bolt flange by the tranny back AKA cat back per say. The front pipe is available that goes up to the V band clamp up under the firewall if you want to add it. Call me if you have any questions etc. Here's a link to a review our the DUAL system in the product reviews section of the site.


http://dieselplace.com/forum/forum_posts.asp?TID=11123&PN=1&TPN=1


Mark @ DPPIEdited by: Mark Craig

Here is a pic of the MBRP SS front-pipe. I have the Cat in the truck right now, but I will get a side by side when I switch them back.


http://www.dieselplace.com/forum/uploads/B83_MBRP_Front_pipe.jpg

I a new here but I bought the 409SS single exit system for my LLY from MARK CRAIG last Mon. got it Wed. and had her istalled in about an hr. once I quit messin' with the damn rubber hangers and used some Penetrating lube to get them off...


I love it so far, took a 6hr. trip to SC on it this past Fri. and liked the sound.. It has a bit of interior resonance at speed before it slips into OD, but I LIKE THAT... I am goign to remove my cat. though and replace it with my buddies old LB7 downpipe, it still isn't loud enough or puffin enough soot for my taste.


BTW: mine isn't throwing any in-cab codes/dash lights, I am sure it will throw codes when I remove the CAT. but if there are any ILL effects of removing the cat. I would love to hear them as well...





GREAT SETUP in my OPNION, wish I had got the 304 though!!!!!!





BIG

Whats the install on the MBRP system like? is it something that can be done with basic hand tools and a good socket&wrench set? also can it be done on the ground? without having a lift? ill be ordering soon, so any suggestions as to where to buy are helpful!


thanks


Jared


Although mine is a LB7...........


I just used a floor jack to get my truck tires on cement blocks, then all I needed to do was remove the right rear shock to make it easier.


What or where did you attach the rear tail pipe hanger brackets, frame or cross member?http://www.dieselplace.com/forum/smileys/Hug.gif


http://dieselplace.com/forum/uploads/AB4_Dual_rear_view.jpg








Thttp://www.dieselplace.com/forum/smileys/Clown.gifNY[/QUOTE]

Here,


MBRP EXHAUST INSTALL (http://dieselplace.com/forum/forum_posts.asp?TID=11123&PN=1)


Just overlook my New England RUST http://www.dieselplace.com/forum/smileys/Embarrased.gif http://www.dieselplace.com/forum/smileys/Cry.gif


http://dieselplace.com/forum/uploads/Hanger_not_installedJPG.jpg


http://dieselplace.com/forum/uploads/Hanger_installed.JPG


http://dieselplace.com/forum/uploads/Spare_Tire_clear.jpg





Thttp://www.dieselplace.com/forum/smileys/Clown.gifNYEdited by: GMC-2002-Dmax

LLY Cat... Or Kill the Kitty!


No codes after 3 weeks, but I'm running the stock muffler. Have not had a chance to dyno yet because I'm "missing" something I need to test with.


Does it improve performance? Not that I can tell. My goal was to reduce backpressure cheaply, which it does. Did it lower EGT's? Here's where I REALLY screwed up. I did not record EGT's before the change.


Is it worth it? Not sure yet, but EGT's under load with the TTS tow tune are ~1250. Stacked with Juice on 3 = 1320. My guess is that it probably dropped EGT's at least 100 deg.

Could someone with the dual exhaust PM me and let me know about the sound and the price of the dual system in409 04 lly cc 4x4 ally

Here,


Hello Tony,


You were most helpful with the information you gave me on installing my new exhaust system although, as hard as I tried. I could not use the holes that you used on your truck. At first, I thought that I had maybe a prototype, rather than the regular production dual exhaust system.


However, after looking at your installation and again at mine. Our trucks are identical except yours is a crew cab with 6'.5 bed and mine is the crew cab with the 8 ft. bed, making those holes in my frame rails further rearward on my truck as compared to your truck.


After being a little hot under the collar and ticked to hell and back. I am real happy with my setup and would most likely do it all over again.


The mild purr and and seat of the pants feel for power makes me feel like it was worth all the aggravation. http://www.dieselplace.com/forum/smileys/Hug.gif


Regards,


Melvinhttp://www.dieselplace.com/forum/smileys/Approve.gif

Glad to here that it worked out for you.


Never thought that a Longbed would be that different but I guess so.


Thttp://www.dieselplace.com/forum/smileys/Big Smile.gifNY

who sells a dual exhaust kit for a lly 2004 duramax.





thanks


pete

Pete


MBRP sells the exhaust you are looking for. Web site: www.MBRP.com (http://www.MBRP.com)

http://www.dieselplace.com/forum/uploads/147_P7040003.JPG


http://www.dieselplace.com/forum/uploads/62Z_P7040009.JPG


http://www.dieselplace.com/forum/uploads/D1E_P7040004.JPG


http://www.dieselplace.com/forum/uploads/353_P7040001.JPG





Glad to here that it worked out for you.


Never thought that a Long bed would be that different but I guess so.


Thttp://www.dieselplace.com/forum/smileys/Big Smile.gifNY





Things worked just fine after I found out that the front pipe needs to be 49 inches and I had to drill holes in the left and right frame rails for the tailpipe hangers. It really looks neat after the installation. The frame rail holes that you used are good for the crew cab short bed. Crew cab with the eight foot beds like my truck, the frame rails must be drilled for the tailpipes. Other than that everything is very straight forward. I just got on the wrong track, until I got good information.


Regards,


Melvin.


http://www.dieselplace.com/forum/uploads/86Z_P7040002.JPGEdited by: GMC-2002-Dmax

Melvin,


That is one sharp looking truck (reminds me of mine)! I think I am going to go with the MBRP now too, but single exit. I'll keep your experience in mind when I get mine.


Dennis

baimpala,


Don't let my experience frighten you. I was under the impression that I did not have to cut anything to make my system fit. After finding out what the exact length of the front pipe and that I had to drill holes in the frame for the rear tailpipe hangers everything went rather smooth.


Now that you know what's to be expected you can install yours without any of the hic-ups that I had. If I was doing it all over again I would still go with the same MBRP system and especially the 304 duals.


I love them, and everyone who has seen them compliment also . . . and I don't regret the initial grief I took installing them.


Melvinhttp://www.dieselplace.com/forum/smileys/Hug.gifEdited by: Melvin Hatcher

petesauto01,


Pete we are the largest USA distributor of MBRP system just call us and we will be glad to help you.


Mark @ DPPI 866-455-7788Edited by: Mark Craig

trapman,


You have mail!


Mark @ DPPI

Melvin Hatcher,


Can't imagine what is different, the 2004's LLY and LB7 we have dealt with were the same as the 2003's etc. I will have to do some local dealership looking this week, maybe our friends at GM dis a switch a roo! WE really apologize for the problems you had, normally it's a straight bolt on and you only have to cut a pipe if you don't have a crew cab, you got hit on both that and the frame holes and for that again we apologize!


Glad you got it on and all is well after all the fustration though, enjoy it and have some fun now that the work is over!!!


Mark @ DPPI

Mark,


If you keep your prices nice and low, I'll have no choice but to keep buying stuff for my truck! Thanks for a nice sale and the fast shipping on my exhaust.


Thanks,
Dennis

baimpala,


No problem, that's what we do. Let us know if we can help you in the future.


Mark @ DPPI