Do high-flow cats make that much of a difference from O.E. cats? Is it even worth the money to get high-flow cats?

assume that the car has no cats and I would have to purchase cats. Would it be better to go O.E. or high-flows? (naturally aspirated vehicle).

From what Karl at AA tells me, the difference b/w cats and no-cats is negligible. E.g., not worth breaking the federal law for.

Where is the bottleneck in the E46 system?

Headers have been replaced ... so, just figuring out which cats to go with ...