I've heard good things about magnaflow's spun metal cats. How good are these things for emissions? I have to pass Maryland emissions.

If I have problems with those then ill just get a Magnaflow direct fit cat. How do I know if the Magnaflow cat is "high flow" or performance? Are all Magnaflow cats meant to improve flow?

Also, could I get a cat with 3in. opening to fit onto a 2.5in. Y pipe?

Thanks.