has anybody done this and does it sound good or bad? How much louder is it than with the cat?

Stock 92 305 TBI

 

It it quite a bit louder without a cat than with a stock cat. Not too much louder than with a high flow cat, just more of a raw sound. If you go ahead and do it, don't hollow the existing cat out. It will sound like crap. Use a test pipe, or have a high flow cat welded in. I prefer the sound with a high flow cat if you keep the manifolds. If you go with headers, then no cat sounds better.

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89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

 

is it deeper with the high flow cat than without?

 

I did that with my exhaust except I have a 3" cat-back with a flowmaster 80 series muffler and Edelbrock TES Headers. I like the sound. You can hear it at my site.

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Eric Natzke
91 Firebird 305 TBI
"It Ain't Stock"
http://members.aol.com/j007golden/91firebird.html
For info on certain parts or mods go to the site below
http://members.aol.com/j007golden/modeval.html

 

I have a high flow cat and a 2 3/4 inch pipe with a 80 series. Sounds good, really mellow but loud really loud.

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Steve
88 Firebird TBI(WS6),TH700R4 - Open Element, Catco 2 1/2 High Flow Cat, K&N filter 14*4 element, American Thunder Flowmaster Catback Exhaust, 180 Stant thermostat, Accel cap and rotor, L98 cam