I am rebuiling my Bronco.
I am getting a long block 351w efi engine and I ordered a set of JBA shorty stainless steel headers.
The question is.....

1. Use a only a cat back system - Flowmaster 40 series muffler - single in / dual out.
2. Cut out cat and use same system as above.
3. Go true dual exhaust - keep two existing O2 sensors, no cat, two mufflers, etc.

 

Selection #1 is the only option IMHO. Even if your are only an off-roader, any law enforcement officer 9including fish & game) can and will impound the truck for smog law violation. Once impounded you have to go to court, have no right to say anything while the judge decides if the vehicle is to be crushed or not- and you get to pay all the fines, tow/storage fees, etc. Even if the vehicle is saved or only cited, it will have to be inspected at a Federal Referee station for the rest of it life.

 

#3 won't work; you're ODBII

What I would do is get a Bassani y pipe.
1995 Ford Bronco Bassani Y Pipe

Or make your own like I'm going to do. Being a 96 you're ODBII you should have an extra O2 sensor behind the cat. Bassani doesn't list a y pipe for the 96, but you could probably just add an extra bung after the cat and be good.

I'm going to cut up an old mustang H pipe I have and use some mandrel bends and a flowmaster 2-1 Y pipe with a 3" outlet into a 3" cat, 3" muffler and 3" maremount mandrel bent tailpipe.

Go to autozone and order the Autozone 577061 / Maremont M30001 tailpipe. It's 3" mandrel bent and costs about $50. You have to cut 12-18" off the front and add hangers, but it fits great. Support the truck and let the rear axle hang and leave 1/4" clearance between the spring and pipe so it's up as high as you can get it. It'll look low, but it's not in the way of anything on or off road. Lots of Bronco guys run this pipe and don't have clearance issues.

What ever you do, make sure you focus on the Y pipe. That's the biggest restriction in the system even with a holed out cat or straight pipe. The bends are horrible. You can even neck it down and go with a stock type muffler if you want quiet and still pick up performance.