hey everyone im new to this forum so hopefully im posting this question in the correct area. so i have a 2004.5 HO 2500 cummins and it has a stock exhaust with the CAT still on. i wanted to remove the CAT and just run a bolt on straight pipe with the stock piping thats there. i am looking just for louder noise and maybe some power gaines. so i guess my question is that if i do this will i lose back pressure (what i heard) or will it stay the same and just be louder? thanks guys hope to hear all your input!

 

Take it off- hang onto it in case you need to for emissions down the road. MRBP has an inexpensive straight pipe to replace it along with other brands. Not sure how much your noise level will increase since I bought mine deleted- muffler swap makes the biggest difference in sound I believe

 

The cat converter is useless. It will in turn make the environment slightly better, but makes little to no difference on our older diesels. If you delete the cat, you will get better flow through the exhaust, better fuel mileage and a better sounding engine! plus in NY where emissions are utter bullcrap, they dont even check for the cat converter. But you should hang on to it just in case! hope this helps!

 

If you are in CA the truck won't pass emissions without the CAT. You don't gain a great deal by removing unless you are looking for big power. If you want more noise just drop the muffler out of the system.

 

The cat is just a restriction in the exhaust system. Same with a resonator. They both create higher egt's. Straight piped is cool for a little while, but eventually the drone of the exhaust will be bothersome. Go with 4" and a "glass pack" style muffler. Turn the muffler so the baffles are closed to the flow of the exhaust gasses. ( Not like real baffles, more like little vents stamped on inner wall of muffler- you'll know when you look through it...)