4" down pipe.

[625fireman]

I am looking at replacing my exhaust. Do you all think a 4" down pipe is over kill. Planning on twin 4" stacks. I already have the 3" down pipe should I just increase to 4" after it or replace it? I know the flange has to stay 3" as that is what the turbo is. If I should go with 4" down where can I get one? TIA

 

[DieselSlug]

I thought the biggest you could go was 3'' due to clearance issues with the frame?

 

[625fireman]

Prolly but somewhere I saw a 4" down but now can't find it. But that was 2 years ago.

 

[DieselSlug]

I would just stick with what you have.... Then just go 4'' on back from there..

 

[thedole]

in this case Big Is Beautifull for sure!!
In a way I think it's a bummer that 3" downpipe is all there is. Wouldn't it in a perfect world make more sense to have it the other way around. Starting at 4" and then step down as the hotter air takes more space then the cooled down air further down the exhaust?

 

[JMJNet]

It would be nice if it will fit. I think the bottleneck of the space is slightly larger than 3". You can go under your truck and see it. It is only about 1cm in between the 3" DP to the firewall. How do I know it? I tried to change GP #8 from under like everybody suggested, my hand won't fit.

Mine is a Suburban, may be a 3500 will fit though.