Catalytic Converter Questions

[HMistica]

I'm thinking about removing it in the future. I've heard it would increase 1-2 mpg by removing it. Can anyone confirm? One of the main reasons I'd like to remove it is to increase sound after I get my dual exhaust system. What's inside the cat? Can you just gut the thing?

 

[2Gen3Gen]

I think this was already addressed. Mileage was the same. Just a bit louder exhaust and the smell of diesel, not a bad dog fart. In my own opinion, I would just leave it alone. But, I don't even change my own oil. I hate getting my hands dirty unless it involves my Corvette. I bought the extended warranty.

 

[macdaddy]

$10. 000. 00 fine and some jail time is possible for messing with the cat. I believe the cats construction is different from the automotive configuration as it pertains to restriction and back pressure.



I am running the straight pipe with the kitty on the 05, when getting on it hard at low RPM you can clearly see the black smoke exiting with with out much restriction when using a turndown.



As far as the sound without the muffler it works for me, very little to no drone when empty, slight drone when under hard throttle while towing. There was a member who had his warranty voided due to the cat removal,you need to rethink removing it.



Mac

 

[Hoefler]

First I would check into your local inspections laws on requiring the cat. I our area, the inspector has to make a visual check for the cat, look under the truck and see if it has one or not. In some areas they have to do a sniff test, actually sticking a probe in the tail pipe and hooking it to a machine that checks for emission compliance, to see if it is working. I removed it, gutted it, and reinstalled it. Now it is a resonator. I am straight pipe to the end now. It has a good drone that resonates through the cab on a good pull. Just cruising it is pretty mellow. Since I tow in the Ozark mountains allot, I have ordered a Flowmaster chambered muffler.



Economy wise, no real fuel savings that I can tell, but the turbo spools up much quicker, engine temps seem to be a bit lower when climbing a 8% 1 1/2 mile hill pulling about 6,000lbs.

 

[JVolpe]

I believed what I was told about the cat being unrestrictive. Mine was removed to "clean and inspect" for problems. It has 28,000 miles on it. Most with afe air intake and Banks Cat back exhaust, and of course some performance mods.



It seems that the cat is a little more restrictive that I was lead to believe. Here are pics looking through the cat. You are looking from in a garage through to the bright sunshine. See any light coming through at all?? The screen your see is on each end of the large portion of the cat. I cant see enough past the screen to see what else or how many other screens there are. The soot build up on both ends of the cat are considerable. You have to decide for yourself if it is restricting exhaust flow enough to affect EGTs or total air flow.



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[Mark Craig]

HMistica,



There are MPG gains to be had by opening up the exhaust system in any diesel, the 2003+ 5. 9 is no exception. The cat that is on these truck is light years ahead of the cats used just a few years ago, but they are still a restriction no matter how you stack it up. I would suggest you get a replacement muffler 1st and see if that helps you enough, if not then get a cat test pipe for off road and racing use and see if that doe the trick for you. Check this site for threads about the MBRP performacne replacement muffler for soem suggestions too. Use the search function. Remember too if you open up the back side with exhaust mods then you need to open up the front side with an intake system like an AFE Pro Guard 7 Stage I or Stage II. a More air in equals more air out which makes better MPG. We have worked with folks on this call us if you have any questions etc.



Mark @ DPPI

 

[Bertram65]

I put a straight through 3. 5" in 3. 5" out Maganflow race muffler on my truck, I have a cat as it is a '03 with MA emmisions, I got a nice increase in sound which I like, but no increasse in mileage.

 

[DIESELWRKS]

hope this helps I straight-piped my truck first and took off the cat, drove around for 2004. 5 2500 QUAD LONG BED 4X4

STAGE I INTAKE GUTTED TUBE, MUFFLER RAN OFF W/ MY KITTY. TST PMAX AUTO-METER EGT AND BOOST 0-60 ON STEERING WHEEL. 285/70/17 COOPER SST. DURABAK COATED ROCKER PANELS AND STEP BARS.

FUTURE MODS VBODIE, TQ CONV AND TURBO.

SOON PUTTING IN MECH, OIL PRESSURE GAUGE.



PROUDLY SERVING AS AMERICA'S

TIP OF THE SPEAR.

UNITED STATES MARINE SINCE 1993a month or so. decided to put the cat back on but I gutted elements in the cat. I had a hydraulic drill from work drilled through in a few spots after this I took a big tank-bar ( bigger crow-bar) and knocked out the rest. I put the cat on the truck and it actually made the sound alittle quieter to me and my wife. I cannot say it helped my egt's I didnt have gauges yet.

it did help my fuel mileage to me. it was right around switch to summer fuel about 1-2 mpg. if you baby it. now it atleast looks like I have my cat still on.

 

[2Gen3Gen]

$10. 000. 00 fine and some jail time is possible for messing with the cat. I believe the cats construction is different from the automotive configuration as it pertains to restriction and back pressure.



I am running the straight pipe with the kitty on the 05, when getting on it hard at low RPM you can clearly see the black smoke exiting with with out much restriction when using a turndown.



As far as the sound without the muffler it works for me, very little to no drone when empty, slight drone when under hard throttle while towing. There was a member who had his warranty voided due to the cat removal,you need to rethink removing it.



Mac

I would check your local laws. Here in Grants Pass Oregon, we smog NOTHING! My corvette? Nope! My Chrysler? Nope... . NOTHING! No smog required at all. .

Im building a new motor for my Vette and when Im done, the new exhaust will NOT include a cat. Heck, the local muffler shop already offered to REMOVE it. I don't and never did like the rotten egg smell that my Vette spewed out the rear and i always wanted it to have a true dual exhaust! Having Oregon plates, I can still drive it into Calif and they cant do squat! I love it here! :-laf Oo.

the cat on my Dodge makes diesel exhaust smell like a bad dog fart!