How about that restricter tube between cat and ****?

[cdennyb]

I've had my '03 now for about a year. After I had it for 4 mths I crawled under and chopped out the restrictive exhaust pipe section (was about 3 1/2" dia) between the cat and the muffler. I replaced it with a section of stainless tubing that matched the rest of the system (4" dia) and picked up about 3 mpg. Any chance I did sumthin wrong?

 

[Whit]

I've had my '03 now for about a year. After I had it for 4 mths I crawled under and chopped out the restrictive exhaust pipe section (was about 3 1/2" dia) between the cat and the muffler. I replaced it with a section of stainless tubing that matched the rest of the system (4" dia) and picked up about 3 mpg. Any chance I did sumthin wrong?

You did nothing wrong, I figger if somthing brakes one must replace it with whatever happens to be layin around the shop.

 

[cdennyb]

kinda bothered me cause it has in real nasty wording in my owners manual that I shoulodn't change or remove anything that might make my truck exhaust louder than EPA and GOVT approved sound levels. LoL. I figured after it was completely out of warrenty, I'd run a set of 5" chrome straight pipes up thru the bed without mufflers, wondering if the local police would be visiting me soon thereafter.LoL

 

[lschultz]

Now let me get this right. You replaced that piece of pipe with a 4" and picked up about 3 mpg.

 

[cdennyb]

Yes, in part. At the time, I changed oil and added the PP additive and started using Diesel Service fuel additive as well, so I can't say all 3 mpg came from the pipe change. The pipe was real weird, it came out of the cat as 4" dia and then had a reducer on it to 3" and a piece of exhaust tube about 26" long and the another reducer going into the muffler which was 4" dia. (??!??) I got a piece of 4" stainless tubing from work, TIG welded it in and it not only sounded better, that's when I started seeing better mileage and actually started driving alittle differently as well.

 

[bentwings]

Stop messing around with all that crap!!! Take it all off. You don't need it and the truck sure as hell doesn't need it. So what if it makes a little more noise. It's a truck. That what my wife says.
I got a solid 1-2 mpg across the board. Plus it isn't too loud unless you romp on it next to a wall or building

bentwings

 

[cdennyb]

Can't do that (yet). it's still got some warrenty left and if the dealer sees I stripped off the cat and muffler the California EPA will send me a donation ticket for a bunch of money. You could twin turbo and car lot full of trucks for the price of that little move! The Kalifornia Smog Laws used to bother cars on gas but they found a new money market, diesel truck owners. (!!) Those ********. Just another good reason to move FROM calicornia.

 

[lschultz]

Don't come to Texas.

 

[haz-mat19]

I lived in Cali my whole life up until 6 years ago, and I don't remember ever taking my '85 f-350 6.9 to get a smog check. After the warrenty is up cut it off. Diesels are exempt from smog, Unless it has changed. See ya

 

[cdennyb]

No, there isn't a "smog check" per se, (yet) but ask yourself...why would cummins put a cat convertor on a 2003 diesel engine if they didn't have to? Read your owners manual too, the part about modifying the exhaust and epa and noise laws and all the other gov't gastopo stuff. If you're engine is still under warrenty, the exhaust is part of it, kinda. It's just gettin worse and worse...remebr when diesel was half the price of gas?

 

[haz-mat19]

Yes I do. I cut the muffler off of my truck, but left the resinator on. It sound better. I have warrenty left, but I am not worried about the exhaust. I did not have a cat so I don't have to worry about that.I know Cali can suck my whole family still lives there. My friend has a Cehvy with a d-max, he replaced the whole exhaust and s@*t canned the cat. I don't blame you about the warrenty, I am waiting for my injector pump to die so I can tap my pump. See ya.

 

[steved]

I thought the 04.5 600 was the first for the cat converter...all the others were just a resonator???

I had been told cali trucks had cats, didn't have cats, might have had cats...here on the east coast, the 600ctd was the first CTD with the cat.

steved

 

[holtzer1]

they put cats on some and not others, there is no rhyme or reason to it, we ordered 2 identical trucks...exactly identical same year options etc, one had a cat, the other didnt. take the cat off, its the biggest restrictor on your exhaust. we've never turned down a claim because of exhaust, a plug in/tap however is a diff story.

 

[Breakin Loose]

If you want to do that 03 exhaust right, switch the cast elbow out for a true 4" elbow off of a 04.5 or newer and then add a 4" downpipe. The elbow on your turbo now comes out at 4" and necks down to 3.5" before the downpipe. I got a 4" elbow from an 05 that was getting an exhaust brake, ordered the stock downpipe from DC and then added a 4" cat-back system. Dropped my EGTs 150 degrees and sounds good.