I was talking to a auto parts shops owner in my local area and he told me
that the reason why my heads on my vanagon are developing small cracks,
to cause small coolant leaks, may be due to the storage and backflow of
heat from the cat? He suggested drilling a hole through the cat, through
the hcomb about an inch in diameter. I am willing to try this if it will
prolong the life of the heads. Is this an okay procedure to do? Any
responses appreciated!

Joe