DieselResearch

Hey everyone. I have a friend who wants to put a 7" exhaust on his 04 cummins. Is there any reason to go so big? He has a bullydog programmer and an intake system. I am not sure 7" is even possible. I told him i would post on DTR and get opinions.

Thoughts???????????

THANKS!!!!!!!!!!!!!

Pooter

I dont think anyone even makes 7" bends to go over the axle and out? I know bullydog makes a 6" system that is a 5" downpipe down to the 6" all the way back. Its really just for sound, you wont gain any more power over a 5" system(and reall even a 4" system unless you're making over 500-550hp...
Hes still also limited to a 5" downpipe anyway, wont fit if its any larger than 5".


I have a 5" straight pipe system on my truck and while I dont need it, my egts are lower and it sounds awesome.

Dodgefan01

Stacked nailed it on the head!

~4" TB is LOUDER then 5"
~5" TB is DEEPER than 4" and a bit quieter at idle and cruising
~7" is just rediculous and GOOD LUCK finding a shop to bend it as it's hard to find them to ben 4" most of the time..

..Just my .02

clemson725

7" is the same area as two 5" pipes. A=pi*R^2

7" = O+V+E+R+K+I+L+L

megacabdad

Is this a stack that he is wanting, or an exhaust under the truck?

mpracehemi

I 2nd this question. Is it a 7'' stack(s) or the whole system. I have a turbo back 5'' that I then converted to 2 6'' stacks., still turbo back is 5'' up into the splitter and 90* elbows then stacks are 6''.

If your friend is going this route, then it's doable and it'll look good if a 4x4 lifted with the whole yards. Like a few has 8'' stacks that look good, they're up in the air with the big rims/tires.

7'' tb can't be done, there's not enough room for it.

Dodgefan01

Heck anything smaller than 7" for STACKS almost looks small

DieselResearch

His father owns a small repair shop and they just bought a machine that is supposed to bend pipe up to and including 7". It is progammable to match the bends need for a specific make and model. He is NOT looking at stacks, but i will let him mess around and make his own mistakes. I will just give my 2 cents and watch.

Thanks

Pooter

You just flat out cant fit a 7" downpipe(not to mention it would be pointless and probably hurt spooling), BUT im interested to see if he can do it, just do a 5" downpipe and do 7" from there back, might have a hard time fitting it if its stock height near the back, over the axle and inbetween the shock/axle...

CTD NUT

Need clarification: Is it a pipe or tube bender? Exhaust systems are made out of thin wall tube. Mandrel bending 4" and up thin wall tube well requires a very substantial investment in equipment. CNC mandrel bending thin wall tube 6" and up is getting into some very serious hardware. This is a far cry from a pinch bender for pipe and conduit or a traditional 3" and down exhaust tube kinker.

XLR8R

Why?......


... possibly a compensation issue?

soulezoo

We can all use more compensation....


I mean money... get yer heads out of the gutter!

TAS05CTD610

So starting a post about 8" pipes would be a waste?

silverrhino

7" is possible under the bed. My old roommate had a 04.5 dually with a 4" inlet/ 5" outlet downpipe, 5"/ 7" reducer and then used a 7" straight pipe and then a 7" bull hauler stack at the end. It looked good, sounded great at idle but at high Rpm it was not a sound that I liked.

txarrowhunter

i wouldnt even think it would sound loud or good.