1 vs. 2 Cats?

I recently put a 3" hi flo Cat behind my ORY so that I could pass inspection here in Missouri. I keep hearing that 2 cats is less restrictive than 1. Why and if so how much HP am I losing?

I haven't heard that, I would think it would be the other way around. A good high flow cat most likely will result in little to no power loss anyhow.

2 could be better because if you think about it, putting 1 after the ypipe you have 2x the exhaust that has to squeeze through it.