'03 Cat removal

**tysmith** · 07-14-2003, 16:26

I'm guessing the cat on my '03 is just an empty can like on my '01 Do*ge. When I put the Banks on that, the cat was basically a straight-through pre-muffler. Is that what I've got on this '03 MA/ME emissioned Duramax? My '01 came from NY - no emissions, and I'm registered in RI - no emissions, but the truck has MA emissions

. Just wondering if all '03's got the cat and the twisty spaghetti exhaust to go with it, and if JK's or Banks' exhaust eliminates the whole mess!

Thanks in advance,

Ty

**GMCTRUCK** · 07-14-2003, 17:13

03 CT trucks have no cat or egr. Since your truck has MA emissions you've got both.

Kennedy · 07-14-2003, 18:45

I've never peeked inside a Dmax cat, but typically, they will have a honeycomb media inside.

I don't offer a CA emissions "legal" exhaust system if that tells you anything...

**BlueOx03** · 07-14-2003, 19:35

Ty,
I picked up my truck in Fall River, it came with the "MA" emissions package as well. I live right up the road and would like to check this out as well. Drop me a line at BlueOx03@cox.net
Later,
TJ

**AlanL** · 07-17-2003, 07:35

I had asked about this a while ago and still haven't done anything about an exhaust.

The advice at the time was that one could replace the entire exhaust system, eliminating the CAT, and that it would have no ill effects or throw check engine lights, etc...

-Al

Inspector · 07-17-2003, 07:50

I have CA truck living in UT. I just recently pulled the Cat out and replaced the pipe with a pipe that would be found on a truck without emmisions equipment. The cat has a honeycomb media as was stated in a previous post that appears to be very restrictive. I noticed that when I had made the change that the exhaust note had changed noticealbly but not badly and that the power was up with a drop somewhat in EGTs.
I also believe that I am seeing an improvement in fuel milage.
I was a bit reluctant to make the change because of maybe causing codes from the EGR to be thrown but that hasn't happened. I have noticed that I have quit a bit of turbo lag now. When it does come on though you will surely know it. A real seat of the pants excel. I'm not sure why this is but would prefer to have better power at the start. I may have to have the computer reflashed but don't know for sure.
Any thoughts?
The down pipe replacement is a straight forward clamp to flange operation. Nothing to bend or clear to fit.
Denny

**DMAX Daddy** · 07-17-2003, 17:08

Banks wants $143 for the piece section of exhaust I didnt get with my Cat-back system. Need to think about that. Of course I stole the rest of the system, but....

**gene smith** · 07-17-2003, 18:53

d-max
i also did not get a down pipe with my flowmaster cat back system, is the banks a direct replacement or is there mods you have to do, also is it 4" thanks Geno

**DMAX Daddy** · 07-17-2003, 19:45

Im not sure, the Banks salesman was kinda weird about wanting to sell it to me cause he knows I have a Catalytic converter. Soemthing about it being illegal in CA to sell it to me and to remove the Cat.

I would hope the part was a direct replacement.

Of course, if others here say no codes are being set, removing the CAT and punching holes through it then replacing it might be another option.

Im still not entirely certain I want to take the Cat off yet though.

Inspector · 07-17-2003, 21:42

I went to a local Chev dealer that has been doing some exhaust mods on new trucks and asked him what he was doing with the removed stock systems. He said we just through them away. I said whats the chances of getting a head pipe from your stack of scrap? He said sure help yourself. I picked one out that still had the paper ID on it. I took about 30 minutes to do the swap.

I'm sure that that doesn't happen at a CA dealer.

Denny

**LA DMAX** · 07-17-2003, 22:14

Hey Inspector,
Any more of those pipes laying around in UT that you can pick up and possibly sell? Thanks

LA DMAX

**Jeep Puller** · 07-17-2003, 22:30

Any word about dealers giving warranty grief over a deleted cat?

**LA DMAX** · 07-17-2003, 22:51

Jeep,
I haven't heard of any out here but if the dealer wants to be an a-hole they can void the warranty right on the spot. Kinda scarry. There was a post a few months ago about a dmax that had injector/piston melt down problems. The dealer didn't honor his warranty, I think because they found out he juiced his truck. Can't remember all the details. My dealer is pretty cool and I wouldn't expect him to void anything.
Later

LA DMAX

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