I have a 99 4x4 V10 and I live in No. Calif. I was wondering abot what happens to the exhaust gas #'s if a person was to gut the cats. Do they really have a function or can the be gutted. I was wondering how other folks have gotten around the emissions testing problem if they have removed or gutted their cats? Thanks for the replies

 

Yes, a catalytic converter does have a function, they burn the unburned hydrocarbons and CO. I had my cat gutted to increase flow and sound, and I was impressed with both results. Truck became much louder and raspier, and freed up some extra torque. I will say though, the truck really stinks. Nobody would ever notice the cat was gutted though, it appears to be untouched. If somebody went out on a limb and tested the exhaust though, I'm sure it would fail terribly.

 

Those cats burn off harmful emissions once they reach a normal operating temp. I wouldn't gut them if they are dual cats..but have them checked to see if they are not clogged.

 

If your in california dont gut it, when it comes time to smog it again it will cost you at least 300 to replace just one for the 318.

 

Normally, you could get high flow catalytic converters for a vehicle. Not sure if thats legal in Cali, but its worth a check.

Its what I did. More expensive then gutting it, but gets you almost the same results and doesn't hurt the environment.