catalytic converter question

[black n yellow]

i bought a 3 inch exhaust set from corksport and dint by the catalytic converter. so i want a high flow catalytic converter will i be okay with just one? what kind should i get and it just had to be 3 inch right?
thank you

 

[njaremka]

metal core are supposed to be more durable, and you really only need one - make sure it gets placed between the two oxygen sensors. for best flow, it should be at least the same size as the rest of the exhaust.