CaughtinmyGrill

Could someone give me an idea of the mileage gain I might get if I removed or gutted my cat on my 04.5 600? If I can gain 1-2 mpg. I would consider taking out the cat and adding a freeflow muffler.

Also, would removing the cat cause me any issues with the exhaust monitors? In Arizona, you have to get tested for emissions every other year.

Haulin_in_Dixie

Basically, if you have to ask then leave it alone. You won't gain any mileage unless the cat is bad and restricting.

Lary Ellis (Top)

Can you say BIG fine? Sure I knew you could........

Federal law regarding that cat, if you remove it, be prepared to have to answer for it. Those EPA guys are getting pretty serious about that stuff.

Some guys who live in the south where there are no inspections can get away with it for awhile, but if you have to be inspected on a regular basis, know they will be looking for the cat.

smiller

So to sum up:

Potential fines & inspection issues + no real gain anyway = leave the cat alone.

mymaur

Ditto!!! On the older 2nd gen trucks they had resonators and muffler. People were insistent that the resonators were cats. I pulled one off one of my trucks and it was simply that a resonator. Mileage increase was zero, turbo temps did drop a bit though.

Your truck actually has a cat on it. It isas illegal as two boys in bed to pull one off. But, if you choose to, you will likely see zero gains in mileage, just a slightly cooler turbo.