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5" Exhaust v. 4" Exhaust

7K views 27 replies 22 participants last post by  LMMBLACKMAX 
#1 ·
Alright going to be ordering an exhaust less the DPF and a chip soon. What I am wanting to know is it really necessary to go with a 5" exhaust or will a 4" exhaust be plenty enough for a truck that is only going to see a chip/exhaust/intake? I had a 5" exhaust on my 5.9L cummins and it seemed like I lost a lot of low end power when I did it. I just don't think the 5" is necessary for the power I'm looking to get out of it and just wondering what everyone else's opinion was as well!
 
#3 ·
Anyone have any dyno runs to prove if it is even worth it or not? I just don't want to lose power at certain RPM points for looks of a system.
 
#5 ·
The sound is MUCH better on 5in than 4...I didnt notice any loss of power on my old lb7...
 
#12 ·
^10-4. I just didn't want to lose any low end power like I did on my Cummins when I went from 4 to 5.
 
#13 ·
The look and sound is the only difference. A diesel should not lose any low end because of an exhaust system being too free flowing. I think that was just an inaccurate butt dyno...... As far as sound goes, its all just a matter of opinion. I personally love the sound the 5 inch makes. I have never heard a person say "I should have got the 4 inch system instead of the 5 inch". Though, I have heard it said the other way. Either way, it will sound way better than stock, and your truck will love you for the lower egts and easier spooling of the turbo.
 
#15 ·
For what its worth..... Diamond Eye is made in the USA. With that said, I got their 5in turbo back kit.
 
#16 ·
i did the DE DP and it was as hard as anybody said it would be. im prolly upping from 4 to 5 soon cause i want the deeper sound and i have somebody buying mine :rof
 
#18 ·
i have diamond eye 5" and love it. sounds awesome.
 
#19 ·
Id think the only "dyno" proof your find is if the trucks over 700 hp :cool:



 
#20 ·
i had a5 inch on my last truck, and now have a 4 inch. reason being is that the 5inch would hit the shock and put a hole in it, and every couple thousand miles i had to re adjust it so it wouldnt keep hitting it. that being said the sound of a 5 inch is not that much deeper imo. also driving with it was bad, there was alot of drone as compared to my 4 inch. maybe i just like the quieter exhaust? just my opinion though, the 5 inch was definitely louder however.
 
#23 ·
for those unaware of owl sound from a dmax
 
#24 ·
Surprising resemblance. :rockin
 
#27 ·
Both the 4" and 5" exhaust use a 4" front pipe, which will limit the flow.

We have a thread around here about the 4" vs 5" power loss and after some research, what we found was that their was a minimal power loss until everything was warmed up. Once everything was a normal operating temperatures, the 5" "power loss" was gone. This should be irrelevant on our trucks though, due to the 4" front pipe.

I personally like the looks and sound of the 5" better, but it's personal opinion.
 
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