I'm in the process of the essential first mods, intake & exhaust. I'm worried about drone with a muffler/cat bypass, so a Rokk muffler is on the way. Is there any performance benefit to removing the cat when installing the new muffler? I know the stock muffler is a little restrictive, but does the cat add to the restriction too? I don't mind losing a small amount of performance in order to keep the truck greener, but if the cat makes a big difference, off it goes..

 

Lost the cat ,gained a stronger fuel odor, a little lower egts, and alot of noise. Not any more resposive, excpecteded a little more.

 

A cat? Did it come with a cat? I do have a large dog. Maybe he chased it away Lower EGT's, but no noticed performance improvements or lose. Does smell a lot better though.

 

*rimshot*
Thanks for the info, guys. Anyone else?

 

All I have to say is read through https://www.dieseltruckresource.com/...76#post1445776 this thread regarding what I saw come out of my cat - restrictive -YES!

 

Todays Cat converters do not restrict the exhaust enough to warrant removing them, plus in Colorado we have emission inspections. Personal opinion, leave it in.

 

Of course, to each their own and in consideration of local testing. However, unless doing something galactically stupid up here, LEO's generally leave pickups alone. No testing up here. I definitely have noticed more bottom end and a faster spool up of the turbo. Additionally, as I stated in the other thread, it is much quieter than I thought, quieter than other third gens I've heard, and much quieter than my buddies '98 he just bought.

 

Had my cat removed in calif on a trip, very obliging shop on the north coast (i run35-40k per year), did not notice any difference in egt or power or mileage, only noise. had it put back on in oregon (we ran 1500 miles for the test). If you look at the diameter compared to a 4" pipe, there is little or no restriction, removal does make everything louder. Removing is not worth warranty issues or federal fines in my opinion. If it helped anything I would have left it off.

 

It is well worth the money to take it off if you pull a trailer or haul any weight. I noticed a decline in EGT's while towing my 30' 5th wheel.