So I got 4 inch dp to back of cab then up to a stack I want to put an exaust on it with a muffler the drone is crazy so opinions on 4 or 5 and diamand eye mbrp farm boy diesel what one I'm up in the air I take the truck on every long trip so it has to be able to sneak under the radar so to speak  all abiding laws aside 

Basically there to disrupt the flow of sound waves in the exhaust that would in turn create vibration in the exhaust and cause drone, without sacrificing sound too much.

Thanks for the info! For me there are pros and cons to the 5". I would like the deeper tone that I think it would produce, and I think it looks cooler lol. But then I don't need/really want my truck any louder. I also don't want the drone to come in at any lower speeds. I also think fitting the 5" under the truck will be slightly tricky. It will definitely be really close to the trans and I'm almost positive there will be no chance of fitting my spare under there anymore. I've also read that going to 5" under 500hp has some negative effects too. So maybe I should try a tip and/or resonator and see what happens.

From what I understand there's really no need for the 5in until you get over 500hp yes, but there's really no negative side effects. Most arguments against it were the need for back pressure but most people have stated that there's no need for back pressure.

Isn't that because the turbo provides back pressure?

AFAIK yes

Backpressure is a variable only for naturally aspirated engines because of the reliance on intake velocity, vacuum, and scavenging in order to best the combustion chamber efficiency.

Charged engines dont run under those same parameters and require zero resistance expelling exhaust as all entering intake air is crammed in.

That said, in case someone asks why not run no exhaust.....  Dont mistake the need for header/manifold tuning which maintains optimal exhaust valve temperatures.....

 

Therefore on a charged engine the more free flowing the exhaust, the better.  But whats ample?.....  Well that depends on the setup.  Stock exhaust mufflers just sucks but if its straight piped or has a sizeable aftermarket straight through muffler then it works.  But a 4" system will prove to be the best intermediate exhaust and more than enough volume until power numbers reach well over 500 HP.

MMine so called drone comes on around 78mph and then it sounds like a semi truck, I got 4" down pipe with 5" rest of the way and 6"tip and also a see through mufler, I really like it.

And yes Katoom you're right it's around 2200 rpm

Edited May 21, 20168 yr by Dieselfuture

The drone will prove to be a problem for just about any aftermarket exhaust system merely because those companies didnt perform all the costly R&D the vehicle manufacture did in order to tune the exhaust note.  Aftermarket exhaust companies tend to simply make it more free flowing for optimal performance.

 

These Cummins engines will always drone around 2000-2200 RPM simply because of the number of cylinders firing per the sound wave traveling speed within the pipe.  Fascinatingly most cars with aftermarket exhaust will suffer from drone around the same RPM range too.

 

The tone of the reverberation can be changed with pipe length, bends, material density, and anything which will change or interrupt the frequency of the exhaust pulse.  The best method is a 1/4 wave resonator tube but ya just rarely hear of people trying it.  Maybe because it can be a little more involved.

 

Here's a terrific write on a how to build a 1/4 wave resonator pipe.  http://www.performancetrucks.net/forums/gm-engine-exhaust-performance-21/how-build-exhaust-resonator-tube-eliminate-drone-489463/ 

Thanks for that link KATOOM, that'll definitely keep anyone busy trying to get rid of drone once n for all. 

 

I do wonder how those would fare against a straight through exhaust since most said it was installed after a muffler.

 

i have to say though, my exhaust and tuning is all stock right now and I still get drone so not sure if we can ever get away from it in that trucks. It really doesn't bother me all that much though, I just roll the windows down and enjoy the sound!

 

 

I have a 4 1/2" DP to full 5" running to 5" stacks. I love the sound and the truck is my daily driver, never gets old to me. For a normal person 4" should do the job nicely. 

I am running a 4" turbo back with straight thru muffler to a 5" tip. There is not enough drone out of it the make it an issue for me. I have had for it 275k miles now and it still works fine. It was part of the Banks Stinger Plus system I put on it when the truck came out of warranty.

I have 5" flopro with muffler and there is a drone at 2200 rpm at 70mph with these 4.10. Drop it down to 1900rpm there is no drone so if you have 3.54 you should be fine.