3rd gen firebird exhaust question

I have an 89 firebird with the 305 and i'm putiing a flowmaster system on it and i need a high flow cat but i wasnt sure which brand i should go with and if i need an air tube to pass ohio emissions tests

CarSound and Magnaflow cats are always highly recommended. You shouldn't need an air tube. But if your current cat has and sensors either before or after, then make sure you get another cat that has those holes in the same places.