I would go with the stock exit and A nice tip as well, or stacks if you want to spend the money.

 

As far as passing emissions it all depends on how they test it. If they do a visual inspection only then you can squeak by w/ a high flow muffler (most are pretty much a straight shot thru anyway) and cut the CAT. The opacity tests it's usually best to leave the CAT inplace and just live with it.

As for federal laws you have to keep all emissions equipment on the vehicle it came from the factory with.

 

if interested I have a 4"-5" turn down tip that looks nice

 

I'm a Cummins guy and I want the noise from the variable vane turbo that is on the Fords

Another vote for the 4" turbo back straight piped and stock exit

Rick

 

If you want to go with a 4" now, from MBRP the 4" down pipe is short of $200, then run a stick of 4" back to the front of the rear tires, and get like a 60* 4" bend and a tip. Mine has a flat bed with skirts, so with the stock opening and no muffler it would vibrate everything in the truck while running 70 with a trailer on. I then put a pipe and tip on it to run it 90* out from under the bed. I liked it but I still wanted to go with my current set up, just because you don't hear of anything like it much. But my way works better with a truck that was quiet to begin with. What I would love to do on a non-common rail Dodge would be to run the old Stingray Corvette style side pipes.

 

Stock exit, I like driving in parking garages and gettin on it a little