3.5" or 4" downpipe for 6speed???

[Muddin]

Hey guys, I will be ordering a 4" tubo back exhaust kit for my '02 7.3L 6spd soon. Someone told me that most guys prefer to run a 3.5" downpipe with the 6spd turcks as opposed to the 4" to maintain more backpressure.


Any opinions either way? Where can you even get a 3" or 3.5" downpipe that will work with 4" exhaust after the downpipe?

Thanks!

[03_Turbo7.3]

just keep your stock one then and get an adapter under the cab from 3.5" to 4"

[Muddin]

Well, I would like the benefit of cooler EGT's from a larger downpipe. However, if it hurts 6spd performance, I will stick with what I have.

So, my question is what are the benefits if any, to keeping a smaller "stock" downpipe with a 6spd? Im running 4" turbo back on my '99 with 4R100 and I love it. I dont understand how the larger downpipe could hurt 6spd performance but wanted to inquire after a friend told me this.

[03_Turbo7.3]

really id jsut use the 4" who care..once its chipped intake and exhaust..power is..there lol

[Stroken7.3]

Mine runs just fine with the 4" down pipe, also I have no muffler and I took the cat off.

[Muddin]

Ok, thanks for your input guys.

[carolinaboy02powerstroke]

6 speed or not a diesel will run better with a less restrictive path...4'' down and 4''-5'' all the way out!

[Muddin]

Yeah, I did not understand how it would matter if it were 4R100 vs 6spd. Just thought I would ask since it sounded a little odd to me.

I'm going to go with a 4" MBRP tubo back kit just like I have on my '99.

Thanks!