Hay man lets just take the down pipe off and cut the cat out and weld a peice of 4in in where it went. it would sound the same and ive still got that left over 4in too.

 

isnt the dp 4 1/2 inch?

 

and theonly thing is is i kinda need that stock dp and everthing in case i have to put it back on you know

 

Removing the cat out of the down pipe won't change the way it sounds by very much. I have the 5" turbo back and it is still quiet.

 

And yes, the stock downpipe is bigger than 4". It almost looks like 5"....

 

o well i heard the it would make a big difference in making it louder that why i was wanting to replace the stock down pipe

 

so it will make no difference at all replacing the stock downpipe?

 

Maybe a little, but not nearly as much as most people think. The variable geometry turbo kills a lot of the deep rumble exhaust sound that you hear in the 5.9. so unless you change that, which even I don't recommend, you will always run much quieter. Plus the 6.7 has 2 pre injection events, 2 main injection events and one final event so it really quiets things down. Sorry.