Info on hi-efficency cats

[BernieP]

I have an 86 3.2, stock except for a SW chip and an MK 1 in 1 out muffler. My car has 105,000 miles and just passed PA emissions. As far as I know it is the orig. cat on it. Does any one have dyno results comparing a new high flow cat with a 20-25 year old original? I have considered going to a pre- muffler but this would require re mounting the cat for the annual emission check.

Thanks,
Bernie