What are symtoms of a cat clogging?

What happens when a cat starts to clog up?

your acceleration will be boggy, may throw a P0420 catalyst inefficiency code, etc

That sounds like what I got. Damn!

lol my new air filter makes my car feel bogged on takeoff so im going to change it back to the other one

Really? What air filter are you using?

^, i agree. Was the air filter you were using that hindered your performance dirty?

I got a cat delete pipe for an 07 Impreza, and modded it, welded it all back together, with both O2 sensors in it with no check engine light!! It was killing my low end performance really bad. Mine were both clogged. they are gone now.

Universal cats are so cheap, you should really try and keep them on the street. What little back pressure they add will improve low end torque. I would get a free flow muffler. Back when all the smog stuff was being figured out, there were big HP penalties, and replacement cats were big dollars. I think the 2.5 engine in my Legacy prolly makes more HP than the 5.0 did in the my 1979 mustang. I dunno if they will fine you if you get caught, but, up here they wouldn't renew your plates.