4 or 5 inch exh.

dieselbeef

dieselbeef

dick doggin
Joined
Jul 23, 2007
Messages
10,001
out the rear. 4 or 5. aluminized pipe. 4''downpipe

dont care bout the sound..quieter is better but im not gonna run a muffler til i see how it sounds inside the cab first
 
Unless you're looking to make over 500hp then 5" is sort of overkill. Plus if youre not looking for loud a 4" should be a little quiter.
 
Imo....the 5" on a cummins has less bark than a 4", when I switched to a 5" on my 12 valve it droned really bad about 70, but it was quieter and had a deeper tone overall. I did a 5" straight pipe on my duramax and I love it.
 
I've had them both and I liked them both. My 5" did drone a little more than the 4" did. Doing it again I would just get the 4" because that's $100 that could go elsewhere.
 
5" doesn't change anything as far as performance because the DP is still 4", it just necks up to 5".

Very different sound, though. My 5" is deeper and more mellow, with a drone at 2k rpm. The 4" is louder and has more of that sharp, raspy Cummins cackle.
 
ARbowhunter7 said:
Well in that case it bottlenecks at the turbo outlet. Same result.
Click to expand...

I wouldn't exactly say it bottlenecks. This is the area where radial flow is converted to linear and there's a reason it bells out

Still wouldn't run 5" hoping for any performance benefit on that app.
 
Mr.T said:
Imo....the 5" on a cummins has less bark than a 4", when I switched to a 5" on my 12 valve it droned really bad about 70, but it was quieter and had a deeper tone overall. I did a 5" straight pipe on my duramax and I love it.
Click to expand...

I love the sound of a D-max with a 5" straight pipe! A buddy of mine had an LB7 with a 5" straight pipe. Sounded pissed off at idle!
 
TheBigNasty said:
I wouldn't exactly say it bottlenecks. This is the area where radial flow is converted to linear and there's a reason it bells out

Still wouldn't run 5" hoping for any performance benefit on that app.
Click to expand...

Where that radial flow converts to linear is a very precise point, a point that probably isn't taken into account by whatever exhaust company makes a (*) flange immediately necked up to a 5" pipe.
 
the 4'' will be here today...

make me an offer on a 6''cat stack with a 4-6 adaptor on the btm. needs paint. exact copy of a cat loader stack.

ill have it on by the weekend
 
I bought my ram with a 4" turbo back, loud as hell. Dont plan on changing it unless I start making over 500 or so.
 
i put the 4'' on w/muffler form silverline. its a nice system. fit pretty good. not fond of the sound but its ok...not too loud which is a plus nnow
 
ive got full 4 inch turbo back (MBRP) with a silverline muffler in the quiet way and its nice and quiet when just driving around but still makes a good noise when you jump on it
 
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