High flow cats on our trucks are pointless unless you are running boost.

 

I am running straight from the second cat out the side of my truck. It doesnt sound bad without a muffler if pipe is ran out from under the cab. And cats do get plugged sometimes, and sometimes it is just after awhile of driving. I work at a valvoline shop and I have seen plugged ones. The usual time frame for a catalytic converter to plug up is about 120k. FLEX FUEL speeds this up. I would also like to know how they do not restict air flow? If they are doing their job, they better be restricting it. The only way for it to actually get rid of the harmful toxins, is to catch the air as it moves through.

Thats my .02

 

x2.

 

Cats are only efficient around 14.7. If you get too rich then they run hot because they are burning off the extra fuel. This is what cakes them out. I wrote a post about an escape I fixed that had a coil malfunction that caked a cat and the details are in there.