I'm getting ready to install my MBRP T-409 cool duals on my LLY and I'd like to know if anyone has left the cat in place but just "gutted" the cat. The dealer would not get suspicious as the cat would still be there, however, I would benefit from less restriction. How about additional noise? BTW, I have a fingers stick installed so I shouldn't get the 401 and 404 codes. MacEdited by: mac1234

Since you're in CA, it might throw other emission codes, and if it starts doing that, you're out a cat to get the problem fixed.



I've heard mixed opinions in regards to straight pipe or just new
exhaust, and believe that in some cases, having the cat is more
beneficial, due to the backpressure it creates (in conjunction with
higher flow exhaust, and/or intake).



I shall be getting the same setup soon, and am going to end up keeping
the cat on, as I've already seen dyno sheets of a before and after test.

Agree with cid, appears to have little if any benefit by removing the CAT. Good luck. JJ http://www.dieselplace.com/forum/smileys/smiley4.gif

THE MBRP SYSTEM HAS AN DOWN PIPE OPTION . SO IF YOU REMOVE YOUR CAT ,TAKE THE SYSTEM DOWN AS A WHOLE UNIT [DOWN PIPE W/CAT ASSEMBLY] YOU CAN ALWAYS PUT IT BACK ON IF EMMISION TEST IS REQUIRED OR IF WARRANTY WORK IS NEEDED.


IF YOU CHOOSE NOT TO KEEP IT SELL IT ON EBAY

Thanks fellas. Looks like the cat stays on for now... Plan on installing system over the weekend. I'll post some feedback back next week... BTW, I installed a Hypertech III last weekend and have it set at stage II. I think it's around 75 hp gain. All I can say is, WOW, what a difference. This truck gets up and moves out now. Now, if I can just learn to keep my foot out of it.http://www.dieselplace.com/forum/smileys/smiley36.gif

I just had the Banks installed and the tech said the same thing
removing the cat helps very little - besides messing around with
the cat and getting caught is VERY expensive.

Removing the cat doesn't help? News to me.......key word is spool up time.....dyno sheets don't tell the whole story.

mac1234, as you can see there are varying opinions on removing the cat's. http://www.dieselplace.com/forum/smileys/hihi.gif Best to do your own search on the forums, see the various posts and decide for yourself. Happy reading! JJ http://www.dieselplace.com/forum/smileys/smiley4.gif

When I put my exhaust on, I didn't notice a big improvement, but I did
notice a big improvement when I got rid of the Cat. Trust me, the
tech that said it helps very little doesn't know enough. It makes
a big difference if <span style="font-weight: bold;">I </span>can feel it.