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Discussion Starter #1
I have a 04 LB7 and as the exhaust curves to go out it has a HUGE catalytic converter, much like the brand new 6.doh F-250's. My truck was not made at the Texas plant, is that thing suppose to be there. Is it hurting me for power..
 

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You must have a CA truck -- you should be able to confirm this using your VIN number (sorry, I don't now what VIN standard is used to specify a CA truck).


Both the CAT as well as the stock muffler are highly restrictive -- especially if you modify the truck.
 

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IIRC, prior to 01/01/04 your truck must have the required emissions equipment mandated by the Federal and 49 State authorities. After 01/01/04, all vehicles for all states would have the same emissions equipment (Cats and EGRs +). The state where you bought your LB7 truck must have had an emissions equipment requirement like CA. I live in Utah (formerly from CA) and when I purchased my '04 in December, it was delivered without Cat or EGR.


A Cat "test pipe" will fix part your restrictive exhaust flow problem.
 

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Discussion Starter #4
If I order a 3.5" or 4" down pipe then do a test pipe for the muffler, do you think my GMC dealership will have a problem with it? Im here in Houston, so there is no emission problems from it.
 

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Powell, I think if you do what I did and just cut out the muffler and then remove the cat you should not have any issues. I did not have a cat so that was not an issue with me at all. Sorry to hear you have a kitty under your truck, better kill it quick.
 

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My understanding is only the CA '03 trucks got CAT's but all the '04's where supposed to have them. But hey, I've been wrong before!!!!
 

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Terrain Twister said:
My understanding is only the CA '03 trucks got CAT's but all the '04's where supposed to have them. But hey, I've been wrong before!!!!

Depends on whether '04 truck is an LB7 or an LLY. I have a '04 non-CA LB7 and it didn't have a CAT...


As far as the laws regarding the removal of emissions equipment from a CA truck in a non-CA state I have no idea. I doubt anyone would ever notice so it is probably a moot point anyway.


Of course this means that the truck has EGR as well -- right? Not sure how hard this would be to remove, but depending on laws and how serious you are about performance you may want to remove it as well.
 

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I have an 03 with a cat and I am in Georgia. There are no laws for them inthe state at this time.


If you take off the cat I hear
that they can be hollowed out with a pipe.


From what I have been told...wink wink...a piece of 1" galvanized pipe and a hammer will clean that sucker right out and all you will have left is a resonance chamber. FREE FLOWING! The turbo will spin up a little quicker. Not sure about exhaust temps as I ...um or the feller who told me this doesn't have an EGT guage as of yet..





Mike
 

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I have a CA 2002 which came with a CAT. I purchased/installed the Banks 4" exhaust which connects at the down pipe (Removes the CAT). My truck has been to the dealership twice since the install. The truck has been up on a lift for oil changes and differential service. The dealer hasn't said anything about the missing CAT. I spoke with one of the diesel mechanics about my exhaust system. He had no problem with it and said it will perform better with an aftermarket exhaust system. The service writer said the only issue would be the emmission system or lack there of. Meaning the new exhaust would not be covered by GM. NOW, If I have an EGR problem will that be covered?


One thing nice about the Banks system, I can reinstall the CAT in about 30 minutes if needed.


ChrisEdited by: CMDMAX
 

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I have a question here,


I have an early '01 Cal delivered truck. It never came with a CAT, it just has that 55 Gallon Drum looking muffler. From what I understand from postings in the past that the '01's really essentially had nothing in regards to emissions controls including EGR's. I had a person late in '02 that wanted to swap me trucks as he wanted a Emission exempt truck as the '02's and beyond required an emission check in California. he wanted to modify away and not worry about State reg's. Is any of this true? I am more curious than anything.


I have not received any notification for an Emission check for my truck to date.


Thanks


Jeff
 

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Discussion Starter #11
I talked to the dealerships around here and they said that they can not remove it, but to goto a muffler shop and have them remove it. Or I could install an aftermarket exhaust system. How much power do you think the truck could be losing if I were to put a programmer or a module on it?
 

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I'll take a S.W.A.G. (I don't know of any test results to support this). If you remove the CAT and replace the muffler with either a straight pipe or a muffler that flows like one, you will likely get a 20 to 30 horsepower increase along with a 125 to 150 degree reduction in EGT (under some conditions with some tuner or module someday, somewhere). Then, if you add an AFE Stage II or similar aftermarket intake your turbo sound like a jet, but I doubt that you will see any change in either performance or EGT (some say the turbo spools quicker, but I don't see it). Hope this helps.
 

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Duramax Dually,


As of this time there isn't any emission testing of diesel pick ups in California


Michigan Joe,


At the very best your not even likely to see a 15 hp. increase. It does lower the e.g.t.s though. tpitt
 

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tpitt said:
At the very best your not even likely to see a 15 hp. increase. It does lower the e.g.t.s though. tpitt

Depends on the truck. A stock truck might only see 15 hp (and I bet it would), but what about one making 600 horsepower? Forced induction minimizes the horsepower gains obtained from intake and exhaust modifications, but the stock muffler itself is very restrictive. Add a CAT to the mix and the exhaust becomes substantially more restrictive.
 

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My understanding is that only the '01's came without a CAT in CA.


Any truck made for sale in CA after the '01 model year came equipped with a CAT.
 

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Blinky,


Thanks, and your input agrees with what I heard. I would have to say that if their are no emission checks in CA then would it not make great sense to remove the exhaust entirely and make it flow properly?


Is there a worry that they might get caught with a modified exhaust?


Jeff
 

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Hi all:

If it matters, I spoke with the Air Resource Board in Sacramento before I bought my out of state truck. True, there is no Ca smog for diesels...yet. Wait until 2006, it's coming.

If you remove that CAT in Ca., make sure you save it and put it back on for that smog test in a few years.

Best,

Dan
 

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My '04 built in 10/03 for sale in Washington State does not have a cat.
 

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My '04 built in 9/03 for sale in Indiana DOES have a cat.

Anyone out there have a definitive answer on why some LB7s have a cat & some don't? Crew Cabs don't & Ex. Cabs do? What gives?
 

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You guys got me wondering about my truck, now. Guess I'll have to crawl under it and check it out ( when I get back home from Portland, Oregon -- nice little town ). I don't think it has a cat, and it's a '04 LB7 Texas truck and I think it was built 9/03.
 
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