I'm considering pipes for the LLY but wonder if there is any worthwile improvement since I have the factory cat.


Does anyone have any facts about installing 4" pipes and leaving the cat that amount to any better performance, cooling, etc? I suppose I was assuming that since I'm already choked up with the cat anything after that is mostly for looks and sound, Is this correct?


I happened to be talking to one of the guys at MBRP today and since they are only 40 mins away may go for the change from stock





Thanks


Rob

Rob, I have the mbrp installed on mine from the cat back. I do have the front pipe but have not installed it yet. I did see a little bit of egt reduction after the install but not like I will when I remove the cat. Mbrp with the cat you still get the perfect exhaust sound. Not to loud but just enough. If I can help in any way let me know.

How much louder does it get when you yank the cat? I just installed a Magnaflow cat-back on my LLY, and the noise is perfect (VERY quiet.) I want performance, but I also like my nice quiet truck.

Gosh, I must be getting old, 5 years ago I NEVER would have considered sacrificing performance for quiet...

I would say it will be a great bit louder. That is why i haven't done it yet even if i do.

Thanks Wakeboarder,


I was concerned about removing the cat as I heard that some have problems, but wanted some gains by doing the mod,


Did you find any better turbo responce?


Damn cats, never did like them http://www.dieselplace.com/forum/smileys/Thumbs Down.gif


Rob

I think I did. The reason i say the is because I don't dive it every day. Usually on the weekend for towing my boat. I drive a 85 Toyota 4x4 during the week to put the stupid mill on it. But @ wot I due believe it is better. I want to put the front pipe on but I know I will have to remove it due to the loudness.

Rob I haven't heard of any one having a problem on a duramax with the cat removed. That doesn't mean that there isn't a problem ether though.

Wakeboarder


I had thought I read a post about some, not everyone, that had removed the cat and got a EGR trouble, (I think) I can't find the post now.


I may just have to throw a set of duals on and see what gives,


Thanks for your input, I appreciate it





Rob

That can get pretty pricey!http://www.dieselplace.com/forum/smileys/Dead.gif

I gutted the kitty and straight piped the lly and havent had any problems. My truck has 5k did the change a bout 2k ago. I dont have any guages yet so cant help you with exhaust temps. Sound is good, barely noticable in the cab but outside is sweet not as loud as a stock cummins until you really get on it. lots more turbo whistle too. Anythig to help the monster to breathe has to be an improvement. Edited by: blkbowtie04