Hey all,
I have an early build 03 Dmax. Jan.-Feb. 03 I want to go with a 4" exhaust and I was looking under my truck for a Cat but I didn't see one, my dealer says I have one??? Is the cat intergrated into the down pipe that has the 4 bolt flange just about under the front floor boards or do I NOT have a Cat???? They have no problem with me going to a 4" system as long as the Cat stays on. If the Cat is in the pipe is there a big difference in EGT temps with the Cat to a 4" Exhaust.. I do tow a TT 7000+lbs and want to keep EGT's as low as possible. No mods or gauges YET. Exhaust then gauges and finally, maybe a Pred. ???
Thanks for all help/answers MICKD

Early 03's do not have cat converters. I know this for certain since I have an 03 as well. I honestly don't think the cat came out till the 04 year, but they may have made the switch middle year.

I have a late '03 with a cat which is located under the passager side rear part of my crew cab. around there anyway.

This '03 Duramax didn't have a cat.

My 04 does not have a cat. either!!!!!!!!

Not fore sure, but i think the cat was introduced when the LLY came out

DURATYS is correct. LLY=Cat.

Some 2003's do have the cat, mine did (Oct, 2002). It depends on which emissions package that came on the truck. I'm still not quit sure how I got a cat on a Texas truck.:confused:

Late 03s had cats, 8th month and on I belive but I would have to check to be sure

what about 2002's

Thanks for your reply's.
I do recall the salesman asking me what emissions package I wanted. I thought that was strange but now I am glad he did.. There were 3 different choices, one was California, which I did not choose knowing the high standards of California emissions engine restrictsions, New York or Vermont State/Federal requirments (reading from my build sheet). If you did not make a choice you got what ever rolled off the line at the time of distribution to the dealerships. Thanks again MICKD

I have a 2004 with the lb7 motor purchased in nov. 2003 and I can not find a cat. on mine either.

I would imagine that the ones with CA emissions have them. Mine does, 03 purchased in Ca.
Cant miss it..passenger side, just under the floor-board.

request a vin check it will tell you for sure,, my 2002 calif had a cat on it . Oh did I say had? Now nice sounding Stan's 4" system that spools up real good //

Hey all,
I have an early build 03 Dmax. Jan.-Feb. 03 I want to go with a 4" exhaust and I was looking under my truck for a Cat but I didn't see one, my dealer says I have one??? Is the cat intergrated into the down pipe that has the 4 bolt flange just about under the front floor boards or do I NOT have a Cat???? They have no problem with me going to a 4" system as long as the Cat stays on. If the Cat is in the pipe is there a big difference in EGT temps with the Cat to a 4" Exhaust.. I do tow a TT 7000+lbs and want to keep EGT's as low as possible. No mods or gauges YET. Exhaust then gauges and finally, maybe a Pred. ???
Thanks for all help/answers MICKD
If you don't see it in front of your four bolt flange, then you don't have one. I pulled mine when I went with the 4" exhaust and it did lower my EGT's (especially while towing).

Hey, I was at your point a couple months back. My 2003 had a Cat on it. This Cat is directly built into the downpipe that come off the turbo, which feeds into the connecting pipe that goes into your muffler using the four bolt flange. I removed the Cat and put on an aftermarket downpipe. It was a direct fit. I got this pipe at http://www.dieselperformanceparts.com/. With my AFE stage II intake, downpipe, and Banks exhaust my truck is mostly ready for any chip or programmer-- haven't decided yet. Good luck with your truck. :cool2: