Exhaust

[firedog]

I will be traveling soon to CA from Ok., I have a 2004 GMC 3500 crew cab dually duramax lly. I'm trying to research possible ways to increase HP and Fuel economy. I have looked in to exhaust kits and chips,after looking under the truck at the exhaust I noticed there is what seems to be a cat. converter between engine and muffler. I was just wondering if there might be some out there that have just taken out the converter and left factory muffler in place, also does this change things for the better/worse in fuel econ or HP and what about emissions for CA.

[JD Diesel]

From what I have herd the lly dont like not having the cat off calif emmissons suck. :mad:

[david]

IF you don't have a calif.truck you can take off the cat and keep the stock muffler with no problem!!
Check with bill heath,he has them!!
David :confused:

[oyazi]

Originally posted by firedog:
.................and what about emissions for CA. CA hasn't implemented biannual emissions insp on diesels ~ yet. However, if you're planning on staying you must register and there is a likelyhood DMV agent may do a physical insp. They did mine ~ but didn't do others ~ go figure. Anyway, I'd say leave it in. It used to be (we're in the 21st century now ~ things are achanging) that the CAT was a big negative. Now, its not looking like the newer freer flowing unit is really an issue. I'd be more concern about the EGR impact on the eng in the long term than I am about the CAT.

[dinoace]

I have also wondered the same thing my 2004.5 "lly" has a converter, and from what I have heard from various sources they seem to all agree that the converter should stay.