I've been thinking of putting on a 4" exhaust every since I bought the truck, and think I am about ready to pull the trigger. I've got a SS MBRP system picked out, but I can't decide what I should do with the cat. There isn't any diesel emissions testing where I live right now (Austin Texas), but there may be in the future. I think I'd like to get a delete pipe, but I can't seem to find them for sale anymore. I think I used to see them pretty regular at autoanything.com (best price I could find on the exhaust), but they aren't showing up on the page anymore. Anyone know where I can get one or happen to know the model number?

Also, any thoughts on the SS MBRP? I don't think that SS is really necessary for where I live (very very rarely any salt on the roads), but I can't help myself......

 

Pull off the cat but save it! you never know...
I got my cat delete pipe from thoroughbred diesel. heres a link i grabbed real quick but you can search around their site to find the right size. MBRP Cat Delete and Muffler Delete Pipes for Diesel Trucks
You should be able to get an mbrp system with the cat delete already but i could be wrong.

I have an aluminized mbrp system and really havent had a problem with it, no salt here either. Only thing I noticed is that when I pulled it off to get the truck smogged, the pieces were really stuck together. Ive had it for over 3 years now.

 

gut the cat and run a 4" pipe through it o and add a muffler. next year texas starts the emmision testing on diesels. then at least you can say you have the cat in case sombody ask. and you will have to have a muffler but you can always take it off if you want. i bought the aluminum cheap MBRP exhaust pain in the butt to install but its good quality.

 

After installing a Magnaflow S.S. 4" turbo back exhaust on my truck, I took my cat, gutted it, then slid it over the exhaust pipe to the approximate location it was before and welded it on. It passes the state inspection every year!

 

What about hollowing it out and putting it back on? Any gain there, or would it be the same as just leaving it on to begin with?

 

Remember all they have to do is shoot a IR thermo reader on your CAT and you are busted. They run hotter than a straight thru pipe.

 

I had mine off for a year then decided it was TOO loud and harsh sounding and reinstalled it. I still have the delete pipe and doubt if I'll ever use it again.... don't have any idea what to ask for it.

 

So it is quieter with the cat in place? Any other negatives (lower MPG, less perceived power, etc)?

 

I took mine off. I used a 4" turbo back off road system from Silverline. I did save the kitty just in case. They are quite a bit quieter with the cat missing. I have a muffler on mine and love the way it sounds with no cat.

 

Personally, I'd buy the "with cat" kit and just swap in the delete pipe when/if you wanted it. Destroying the cat means you'll blow a few hundred to replace it if you ever need it or just decide you don't like the whistle. I can still find the delete pipe at several places, but maybe they are sold out and just don't show it.

MBRP Cat. Test/Delete Pipe

It's not hard to tell when a 6.0L doesn't have a cat.... rumble aside the 747 sound is a dead giveaway, I think a mechanic would have to be deaf to not catch on to a gutted cat.

 

I'm thinking of doing the same thing. Does the cat need any modification to be able to fit a 4" system?

I've always had a buddy's shop do my exhaust so I've never dealt with the kits you put together yourself. It's always been the seamless system from the headers back. Not sure how the clamps and everything work.

 

There is a flange on one end of the pipe. I believe it is only 3.5" too.

 

Take it off and sell it to me cheap!

 

No other negs......these cats flow really good!

 

I'm thinking the same thing... if I get a delete pipe, the cat will be going on a shelf 'just in case.' No one has really answered my question though as to what advantages there are to running without a cat. Is it ONLY sound, or are there some extra MPG or power to be gained?

***EDIT***
BPofMD beat me to it! I had just hit reply and read your message. Now I just gotta round up the funds! I wish I could make myself look at the cheaper kits, but there is something about SS that I just can't get over!