Really High Flow Cats

[MearCat]

I got thinking about high flow (or high volume) cats/catalytic converters the other day. There has always been talk on many forums about some cats flowing 700CFM+ and others flowing "only" ~500CFM but what I want to know is... over a certain flow rate does it really matter?

I don't kow the forumla for working out how much air is comsumed/expelled by the engine under a specific boost (can someone help with this), lets use a baseline of - A 2.5L engine running 12psi @ 6500rpm.

I DO NOT want to know that this brand cat has this flow and that brand cat makes that flow, I'm simply trying to determine is it realy worth chasing a cat that flows 700CFM+ if all your engine flows at peak rpm and peak boost is eg 500CFM.

[Beer Baron]

should be easy to messure on a car. put a fitting pre-cat and attach a boost gauge. if you got pressure, you got restriction. next replace cat with piece of pipe. if you still have the same pressure, then it's just the exhaust, not the cat. if there is less, or no pressure then definately the cat is a restriction.