Tree DR

Any time I get above 2,000rpms the roar is to much. I bought this truck used so I'm not sure what was done other than the obvious stainless tip at the rear of the exhaust and the exhaust brake. It still has the resonator and muffler, intake is all stock. The stainless tip on the exhaust has a rolled edge that wouldn't cause all the noise though would it?

Lark

You're sure it still has the cat behind the turbo? I took mine off for a while and I couldn't not stand the drone inside the cab!

Tree DR

Cat is still there only thing I can see is the SS tip that is different. What kind of welds are there at the ends of the cat? Maybe they gutted it?

Lark

Very likely. May be worth going by a muffler shop and having them cut it off and checking. Shouldn't cost much more that $40-$50. If so, then that's the problem.

Lark

Actually, easiest way to tell is do you smell diesel? It's very stong without a cat. If not, then it's probably not gutted.

Tree DR

Diesel smell is strong. What's the best route to go to kill the drone?

Lark

Maybe you can find someone on here that doesn't want their cat and you can pick it up? A lot of people get rid of them.

I spoke to this guy...

http://www.dpsdirect.com/

...when I was having the same issue (I didn't realize the cat played such a big role in the drone) and he said on these newer Cummins the drone is VERY pronounced without the cat. He said he leaves them on because they only contribute about 50 degrees to EGT and flow very well. He said most of the heat and restriction comes from the stock muffler. I put mine back on and he was right.

I went with a 30" Magnaflow and I'm very happy. Almost as quite as stock, which I like, but much better performance and lower EGTs.

The other option is to put a 54" (I think that's the size) Donaldson muffler under the truck, you have plenty of room. This is actually a muffler for a semi...

http://www.donaldson.com/en/exhaust/...ent/index.html

That should get rid of the drone AND serve as your muffler as well.

morkable

I second the donaldson idea, but be careful, there was some discussion a while back on here about the differences in the units. some of the donaldsons dont flow as good as others. But you can find this info on thier website

Kevin

Fisherguy

I got my 40" Nelson from the local Cummins shop for $67 CDN. The body is longer than the stock one but it's 4" straight through, no baffles at all.
Trying to find a place to do the install which is a little work with the offsets being different.
The guy I went to yesterday goes to a shop where they make exhaust systems for trucks, they can bend 4" pipe, your normal muffler shop can't do pipe that big.

Word on here is it'll sound great if you leave the cat in place.

Tree DR

Well there is one advantage to haveing a drone. Because it starts after 2000rpm. You keep it below 2k which means better mpg.
Well there has to be a few loose cats around here some where. Probably could find one if I looked in enough barns.

Lark

That hasn't been the case with me. For some reason my gas mileage has been better around 75 (GPS speed) then 70. Now with the 315's, I need to run closer to 80.

TurboTed

If the cat was cleaned, you may want to go with the 52" Nelson. Get the free flowing muffler. No drone at all.

Tree DR

Are you saying to put a 52" Nelson in place of the cat and stock muffler? Or just replace the stock muffler with the Nelson and leave the gutted kity?

Fisherguy

From what I've heard from more than a few people, removing the cat will give you the droan.
Ask me Tuesday after I get mine back...

Lark

I'll bet ya a boat you'll have a drone.