what to expect from a high flow cat?

I'm just about to put a Focuz high flow cat on my integra. What kind of HP gain can I expect from that ?

I'd say maybe 2-4 horsepower, maybe. But what I noticed was that first of all, it sounds like ass, and secondly I have even less low end torque.

my friend has a carsound high flow cat and it owns. sounds so deep with his BOMB tunable muffler off ebay (i had that same muffler)...

i hollowed my cat and it just sounds a little louder, not any more like ass or more deep

what about a straight/test pipe? how much more power?

what about a straight/test pipe? how much more power?
Well you need some backpressure with an N/A engine. Actually, with Honda they need more than most others. A high flow cat will probably yield you more power than a test pipe. But it depends on what muffler and size pipe you use too. An example would be: DC Sports 421 header, test pipe, and Greddy cat-back would probably get you 15 HP over stock. Greddy is slighty more restrictive, but with a testpipe it actually makes more power. Now a high flow cat and a straight through muffler will probably make the same power, maybe not as much low end torque though.