When i purchased my 03 2500 4x4 hemi it had the "fake" (single in-dual out muffler) dual flowmaster exhaust on it. I still have the same basic setup except i have removed my catalytic converter and replaced it with a y pipe. So with the y open its loud as hell and with it capped off it runs through the muffler as usual. It'd be nice to get an electric cutout so i can open or close it with the flick of a switch. To bypass the CEL problems with the o2 sensors i did the nonfouler trick. I want to try to get true duals with the exhaust exiting through the rear tailpipes because right now with the y open around 2000 rpms it has this annoying crackling sound, probably because the y pipe is directly below the truck. I think it would sound better if it exited through the rear. But my main concern is what would i do about the o2 sensors? I was just thinking just leave them in one pipe because it would still get the same readings, just less flow. Is that how one would go about doing this? And i hate to bring this up but has anyone test fitted or installed headers on a 2500 hemi? ive been on every forum possible and everbody says even the ones listed for a 2500 probably wont fit. Ive only found one set that is gauranted to fit but they are custom and are over 1k. Thanks Isaac

 

C'mon, theres gotta be somebody on here with true duals

 

Last I heard the only option for a 2500 Hemi was custom headers.

As far as "TRUE" duals, I've never been a fan, have always connected the two sides with either a "Y" "H" or "X" pipe somewhere. Right now I'm going with a custom "Y" just before my SI/DO muffler to balance the two sides with cats still in the system, just moved back about 14" to accommodate my LT headers.
In my 2nd Gen Ram (5.9 gasser) I had dual starting at the manifolds to two mufflers and welded in a simple "H" pipe just before the mufflers, no cat and used the non-fouler trick...

 

It's been proven that a connecting middle pipe such as an X or H pipe increases output and flow characteristics.
With that said, I would still classify true duals as any exhaust that doesn't have a Y-pipe. a Y-pipe joins headers together and removes the fact of having such a thing as true duals.

 

Alright I think I am gonna do a x pipe setup and just try to make my own headers. I've seen some header kits with the pipe and flanges, it doesn't look too hard. I already have the dual exit muffler with 2.5 inch pipe, would it really make a difference if I went up to 3 besides sound?

 

Why not use a DI/DO muffler? Same as having the "X" or "H" in the piping, and saves a lot of work in the setup. My Magnaflow DI/DO is basically nothing more than a big "X" on the inside, and is the only place exhaust from the two sides meet.

 

That's basically all I did on my current truck. Completely dual down to about a foot before my SI/DO muffler where I used a less restrictive than stock "Y" adapter, then out to twin tail pipes. I let the completely open save for a small wingplate muffler balance out the two sides. Was much easier than the two muffler and "H" setup I put on my 2nd Gen Ram...

 

Going that route now. 3" duals all the way to a Dynomax Ultra flo X muffer then turn down before the axle.

 

So did you have the 02 sensors in a single pipe before the H pipe?

 

My 2nd Gen was a one cat truck so only one pre and one post cat sensor. On it, I went with no cat and I welded a couple of nuts (bungs) in place, plugged in the pre cat sensor right into the pipe and did the non-fouler trick for the rear (post-cat) sensor so I wouldn't have to look at an annoying CEL.

Since Hemi Rams come stock with hi-flow cats, I retained the cats, just moved them back about 14" to accommodate the LT headers, spliced in some wires to extend the post cat sensors and just put them back in. Never a single CEL to date.