If you live in NY, you need to get the catted one and also make sure you have flash pro. You will need it to get the most out of your parts and for your car to run correctly but also to pass emissions.
I lived there for years, they plug into the OBD port and hook up to some computer system. If any of the emissions sensors aren't working/reading they may fail you. Especially if they can visually tell that some parts have been changed.
Flashpro can take care of a lot of the "ready states" on the sensors and stuff. Plus its just a good place to start even if you do nothing else to the car.
Advice on inspection/emissions in NY with a modded car:
I found Valvoline oil change places to be the laziest about inspections since they don't make any $$ on them. They still plug in but unless they can snag you on something they can service they won't mess with you. Obviously they will fail you for bald tires and such but they won't be looking for work they can't do. Full service shops look for stuff they can charge to fix. You have to call ahead for an appointment at the valvolines since they don't want to do too many and lose $$. Costs the same everywhere anyways.
I got failed at a local garage and they wouldn't give me a sticker since they said I needed brake work and they could do it on the spot for $300. Took it to Honda the next day and they said my brakes were fine. $20 for the second inspection but oh well, better than $300 to some shady garage.
For non-NY'ers, if you pull in for an inspection, they scrape your old sticker off before they start. Now if you fail you have no inspection sticker and thats a nice ticket. Very easy for the cops to spot too. You can try and drive around without the sticker on your windshield but good luck. Great way to trap people and force them to pay for on the spot repairs to pass. Real scummy places will call the local cops for an easy ticket. Seen it.