I'm a bit off a noob around cars but i'm learning. I was poking around the forums and I see alot of things refering to a "catback exhaust", does that just mean there is a cat on the exhaust? I see when you buy a muffler it says it's a catback, does that mean you can use it on a catless system? what are the advantages to a catless system? also what does a resonator do? Thank you :thankyou: