Cat Bypass

[Chris Wiles]

Is a Cat Bypass worth doing to a 1991 stock 964? Is the performance difference noticeable?

Christopher

[Don Plumley]

I'm not a 964 expert (Bill is much better qualified) - but I know the whole exhaust system is somewhat convoluted. The biggest benefit of removing the cat is lower engine bay heat and a little less weight off the tail end of the car. I doubt there is much if any of a performance difference.

[Bill Verburg]

A 964 cat by itself weighs 13#

here are the flow #s for each of the stock 964 components

Section Flow Rate (CFM)
Catalytic Converter 442
Primary Muffler 396
Secondary Muffler 462

As you can see, the primary restriction is in the main muffler, followed by the cat.

[Chris Wiles]

So by what your showing me the restriction at the muffler would stop any performance increase by the cat bypass? Is that right?
Thanks in advance.

Christopher