Needing to replace my current cat back exhaust after 10 years or so of service. What are the pitfalls - aside from cost, of going to a true dual system with high flow cats into performance mufflers? I currently have a single line into the muffler and then duals from there. Will I have O2 issues with just one sensor in one side? Any idea if this is legal since it came with the single cat?

 

Pitfalls? Noise. What motor do you have? Changing mufflers has no effect on legality.

 

Have the 5.8L. Not the mufflers but going to dual cats from a single cat system.

 

so your going 2 high flows and keeping your current muffler setup? Thats going to quiet it down a lot and kind of unnecessary. Whats your reasoning for doing this?

 

Sorry for the confusion. I am thinking of going to two high flow cats and two high flow mufflers - a true dual exhaust right from the headers. What I have now is the stock system where both headers go into a single cat and into a single muffler and then branches out to two tail pipes.

 

Dual hi flow cats won't make you illegal. And since you don't live in cali you don't have to worry about any smog issues either. But since your doing all this I assume you want to get a little more performance and better sound out of the exhaust so you might as well do the headers too.

 

You should look in the forum exhuast section there is a sticky over there that would answer most of the questions here..
https://www.f150online.com/forums/ex...ust-guide.html

 

A lot of material in that thread. My biggest question - aside from the legality of going from one to two cats is the effect on the computer. Since the 94' 5.8L does not have MAF and the computer is not really programable will I screw up the performance instead of making it better? Will it throw codes etc.? I currently have one O2 sensor in the common single line going to the cat. Does it matter which individual line I put the sensor in with a dual system, do I need two sensors? Obvioulsy I don't want to go through this expense and wind up with less performance or other problems.

 

This should really be moved to the exhaust thread.

 

A 3 inch single in single out is the best set up for the 5.8 and the factory cam. From factory these trucks had a pre cat and a regular cat behind it. I know here in california we cant mess with the cats anymore. It has to be approved for your vehicle.
Check this thread out.
http://www.fullsizebronco.com/forum/...EXHAUST+THREAD

 

So I should leave the single line through to the muffler and then branch out into dual tailpipes like I have? No benefit to making it a true dual exhaust system? What about eliminating one cat and replacing the OEM with a high flow?

 

If you go true dual make sure they put an H pipe or X pipe in there to connect them... I had true duels on my '97 w/o one and it sounded horrible. like two 4bangers getting into an argument going down the road... hahaha...

Though, I had no cats, just 1 flowmaster on each side.