i have a 2001 heavy duty 3500 5.9l with 2 factory cats, into 1 muffler and single 3" tailpipe. i have read all posts back to january and have read no posts about with this setup. it seems most often the thread is about single cat in and dual out. went to exhaust shop to get price and mechanic recommended 2and one half inch out tail pipes. this will be the setup. 2 factory cats, 2 flowmaster super 40s muffler, custom bent 2and one half tailpipes, with 3 inch stainless tips. all for $450.00. i would love to have some opinions. will have system installed next saturday.

 

You do have more options...
to have true dual exhaust you will need to get a O2 simmulator because you cant cut off your cat because of the o2 sensor behind the cat. if you cut the cat off without getting a o2 simm then the engine computer will sense something wrong and the engine light will come on and the engine will run worse. You can get an o2 simm from www.thefastman.com and other places. The setup on my 01 dodge 5.9 is a catback setup. I have 2 40series single in dual out flows that are behind the cat and connected to a custom built Y-pipe. I love this setup! to get more info and illistrations check out the thread "flowmaster 50 series suv muffler" I made alot of posts about this setup including places to get the flowmasters new at half the price. This thread is recent and in this forum...2nd gen dodge. Hope this helps you. -Tyler

 

i do not plan to remove the cats. as i mentioned i have 2 factory cats with 2 inlets to muffler and one exit for tailpipe. they are going to cut off muffler only.this will be a true dual exhaust system. my main concern is losing low end power due to 2 and one half inch tailpipes. i know that i will increase top end. but do a lot of towing. also to note that both cats have a one inch crossover y pipe connected together running to o2 sensor. any more suggestions would help. thanks