Just picked up another addition to the cummins family. 2007 5.9. Plans for now are just exhaust and intake other stuff down the road if/when tranny has issues. Have other ones for go fast. Anyways, I can't decide on what exhaust. 5in or 4in? Kinda like sound of 5. Both would have muffler. I want a full kit. Which brings on the next question... What company? Leaning towards magnaflow or mbrp but idk. Let me hear all your opinions.

 

Ya looking for Aliminized or stainless? If youre gonna be pushing some serious hp in the future, then go with the 5 inch. But if youre not, then the 4 inch is plenty and will easily handle up to 500 hp. As for brand well thats pretty much your choice. Im running aluminized 4 inch AFE turbo-back with aeroturbine muffler. Although, a few years ago I found a brand new 5 inch tailpipe section on ebay for $60 bucks shipped. I bought it and installed it ( for ***** and giggles) and added a 6 inch stainless tip. Looks cool but did nothing for performance, just a tad louder (wanna-be 5 inch I guess). A 5 inch system does sound pretty sweet tho. Just depends on what you want vs what you need. Im sure there is a price difference between the 4 and 5 inch, but Im not sure how much. There are numerous vendors on this site that will help with pricing.

 

I just went with cat back Magnaflow dual exhaust. I love the sound of duals with the Cummins. I picked up a whole mile to the gallon in town too. It is as quiet as stock when driving normally, and makes a melodious sound when under full throttle. It is a four inch exhaust, one muffler then into duals.

 

Thats sweet! If ya take a road trip, you'll notice better hwy mpg as well. I do like the look of duals. I shoulda done it when I replaced my stock system several years ago.... Lose the cat and you'll get even better mpg, and cooler egts. Enjoy!

 

I helped my friend install a 5" Magnaflow ss turboback on his 5.9 '05.
Results were severe drone,no measurable increase in mpg or performance.
Due to emissions here he reinstalled the stock exhaust but with a Donaldson straight through muffler and all is well.

 

I met a guy that had a donaldson muffler on his highly lifted 3rd gen CTD, at a truck show, and it sounded pretty darned sweet (never having heard one). Note to self......

 

Stock system is already 4". Just dump the cat and muffler. Way better sound and completely unnoticeable in the cab when cruising. Give it throttle and you can hear the nice unrestriced note.

 

One man's unbearable drone is another's purr I guess.

 

Seems the younger generation likes the loud exhaust, and as you advance through the years, it gets more and more annoying. Im there now, as I like my trucks quieter. I get more pleasure hearing my turbo sing, on my CTD dually, and hearing the whine of the supercharger on my gas Chevy dually. [B]BUT, burnouts can never be loud enough.......just me I guess.

 

I use this truck to pull my loud car haha. I need some quiet after a day at the drag strip.