Well as it starts today my cat broke inside so i went to get a new one put on and after they put it on i felt a hugh power lose the cat is a little longer then the stock but can that really be what it is? Help please any suggestions!!
Maybe the one you had was a high flow cat? Maybe the one they put on is a generic cat that wasn't deisgned to work specifically with the miata? Those are the only things I could think of. I don't think it's possible to put an OWM cat on backwards as it will only go on one way. And even then, all the cats i've seen the insides of were just a honeycomb, so it's not exactly unidirectional from what I can tell.
Another possibility is that your old cat had been torched on the insides and wasn't reducing emissions properly thus creating a high flow cat of sorts. Do you have headers, turbo, or anything else that might create better exhaust flow before the cat?
Even if the old cat was totally blown (straight pipe) the difference would be minimal. 1-2 hp tops (dyno proven!). I highly doubt that you would feel a difference. Hear a difference yes, but not feel it.