4in vs 5in exhaust. Yes i know another one.

[Daniel McCurdy]

I know its been covered to death but i couldnt find quite what i was looking for. How does a 4in straight pipe compare to a 5in with a resonator/muffler. Im mainly concerned with the drone i really dont like it. As far as actual noise well, currently it has a 3.5in straight pipe that exits right behind the cab and the engine makes so much noise you cant really here the exhaust inside the cab.

 

[Clb]

Volumetric efficacy asks why a 5" pipe is even considered ...
Just my .02
Didn't Mell do a pipe test at dyno days once?

 

[Daniel McCurdy]

yea, 5in is completly overkill for any idi, but it wont have an idi forever eventually it will have a 550-600hp compound turbo cummins so i was thinking a little ahead i only want to do the over axle portion of the exhaust once

 

[Clb]

Then you may want to consider posting this in the cummins forum for real world input...

 

[notenuftime]

Those big exhaust look goofy in my opinion. Don't do nothing but make noise, but everyone should build their truck how they like.

 

[IDIBRONCO]

Those big exhaust look goofy in my opinion.

What? Not every diesel has to have a drainage culvert hanging off of the tail pipe?

 

[Laine D]

I ****** love my 4 inch exhaust. At straight pipe. No drone. Quiet inside and rowdy outside. My turbo made it sound much different as well.

 

[Daniel McCurdy]

4in would definetly be a lot easier to fit in there

 

[IDIBRONCO]

I ****** love my 4 inch exhaust. At straight pipe. No drone. Quiet inside and rowdy outside. My turbo made it sound much different as well.

Yep. I'm going with 4" on my trucks. There is no need to go larger. A turbo does certainly quiet the sound down a lot.

 

[Daniel McCurdy]

The stainless kits im looking at are all over 400 seems extremely high to me. I dont really think it would be to hard to build it myself for way cheaper looks like all i need is a couple 90s some 45s and itll be good

 

[IDIBRONCO]

The stainless kits im looking at are all over 400 seems extremely high to me. I dont really think it would be to hard to build it myself for way cheaper looks like all i need is a couple 90s some 45s and itll be good

Basically that's all you need. That and a straight piece or two.

 

[ih8minimumwage]

4" is around 45ish off the downpipe and straight all the way back. I still need to install my 90 for the exit versus the current dump after the rear axle, but there's plenty of room under these trucks for 4".

 

[Daniel McCurdy]

Yea, i was thinking taking the exhaust over the axle all the way out the back vs dumping it in front of the axle. It would be a lot easier to just dump it in front of the axle

 

[notenuftime]

Mine is 3in into a side pipe. Sounds good to me and don't have to mess around with the axle, I guess little cheaper also.

 

[Daniel McCurdy]

I had seen a few people say that having the exhaust in front of the tire can cause extra tire and break wear because of the extra heat and in the winter it can freeze the breaks cause of the moisture. Of course dont know how true it is but i can sorta see it