MmmDieselFumes

Well, I've got this smoke box that I fabbed up at work (4"x6"x5' square tubing with endcaps) that I planned on using for making my dual stacks (was thinking dual 5" with a 45-75* miter), when I got to thinking about having the pipe made to route up into the smoke box.

See, I have 3.5" pipe ran from my stock downpipe right now, but was thinking about putting a transition to a 4" pipe and then route it up into the smoke box. Would it be pointless to do this, and be better off just running the 3.5" I have now, or should I hold off and get a bigger downpipe, and then route some 4" up into it?

Just wondering what the common consensus was for these type of things?

dieselfuelonly

I would get a 4" downpipe if I were you, but you don't necessarily need it.

CTD03

go with the 4 better sound and it cools just a little easier

you wont be disapointed at all going 4" all the way

the you can support 600 hp at least with the 4" and not have to worry about upgrading pipe if you ever decide to bomb your truck big time

MmmDieselFumes

How much do downpipes run, and how much cooler are they? Cause I can run 75mph at 2,000rpm at ~8-10lbs boost and around 750-800* by the pyro (temp is a guestimation. blown turbo boot so I don't remember the real number)...

fiveology

Go with the 4 inch. I ran my stacks that way for a while ( stock DP and about a foot of stock pipe, then transition into 4 inch up into the bed and cross pipe ). That way down the road when you buy a 4 inch DP you won't have to redo your whole exhaust to make it work, you'll already have 4 inch pipe in there.

dieselfreak12

You can get one off of ebay for about $150 but i can't remember if it was a 5in or a 4in???

Buckshotram

I bought a 4in dp from rpmoutlet.com for $100 and have about a 4ft piece of 4in going into my ypipe for my stacks.

MmmDieselFumes

Yeah, I keep on going back and forth between using the smoke box I made, or going with a ypipe. I really haven't heard too much about the pros/cons of one vs. the other.

Probably go with that 4" dp, then try to find some of that 4" flex tubing to route it to either the ypipe or smoke box.

Then again there's still the question whether I should use alot of that flex pipe (no idea where to get it either), or have a shop do the bends for me on some plain old 4" straight pipe...

I dunno, too many dog gone options!

Southern Pride

you can get flex pipe at just about any 18wheeler mechanic shop. i got mine from Smarts Trucking in Beaumont, Tx. theyll cut however long a piece you need. i saved money not getting the exhaust clamps for it. i just welded the flex to the 90 that tied into the t-pipe in the bed, and welded it to the existing stock pipe. i used some 5"to 4" reducer, then 4" to 3" reducer to the stock pipe. i tell you what, it was a trick to weld that thin flex to the exhaust pipe. i used a mig, and it wasnt that hard once i figured the right temp and wire speed. ill eventually through in a 4" dp to the flex. i am going to make me a "smoke box" as well out of some square tubing as well. i got some pretty awesome 8" black stacks off a couple of RATCH's over here at the air station that are gonna look sweet.

MmmDieselFumes

Black stacks hmm? That sounds awesome...

So why you thinking about a smoke box, are you not happy with your ypipe, or you talking about for a different vehicle?

Southern Pride

na, i put my whole system together myself with 2 buddies of mine right after i got back from iraq the first time, so i was chompin at the bit to git it done. it looks fine, its just that one of my stacks is rusted pretty bad because of the whorish wife (long story), and their only 5"x36". now everyone here at camp lejeune has stacks, but noone has any that will look like the ones i got and they are pretty stout. i just got to figure out how to get some reducers to get them to fit on some square tubing. the pipe is starting to rust in my bed pretty good, cause thats all i could get my hands on at the time. the smoke box will last a lot longer and will be stronger. thats what most loggers in my area of texas use on their trucks anyway. but i love my stacks, and wont go back to having a "regular" exhaust.