Pros & Cons of cat gutting.....

[PKRWUD]

Originally posted by sn95gt19
i never knew that there were only 2 "real" cats and the first two were only pre-cats, when i hollowed them out the front two had the same exact insides as the rear two, i always wondered how they could get away with only putting two cats on aftermarket pipes, i just dont understand how they could be pre-cats when they both have the same insides. if you want to explain it, im up for learning something new

The honeycomb in the pre-cats is coated with a rhodium/platinum catalyst, while the honeycomb in the regular cats is coated with a platinum/palladium catalyst. The pre-cats "work" when the exhaust is too cold for the regular cats to be effective, but really only do a halfassed job.

Take care,
-Chris