My bronco II has 2 converters.Would gutting 1 or both of them help or hurt gas milage and performance.Thanks.

 

Gutting the cat without installing a pipe to connect inlet(s) and outlet will hurt both. Magnaflow offers a decent replacement cat for the 2.9 Rangers/BIIs. Is your current cat acting like it's clogging/clogged?

 

I did an injector cleaning through the plenum and i heard carbon going through the exhaust.I feel like it might be trapped in the first cat.Why would it hurt if i gutted them or just one of them and put them back on.Thanks

 

I see. I've never noticed any issue with doing injector cleaning with the injectors still installed, but anything is possible

Think air flow. With no 'direction' for the exhaust to specifically go, you're just pushing exhaust against itself because it will re-direct itself when it hits the rear part of the internals on either side of the outlet. Essentially, it creates a backflow/backpressure that causes more performance issues than it helps. This is why they used to make / sell converter test pipes.