Got the code checked out and it said, "Catalytic Efficiency". Does this mean my cat is clogged? The car still feels strong and responsive to me?

I got an appointment with Straight Line Performance on the 28th to get my Nitrous tune and this crap pops up. I don't have enough cash right now to go headers and such but I'm worried about having a clogged cat mess up my numbers.

 

Catalyst efficiency can mean either a manlfunctioning cat or a bad rear O2 sensor. If it doesn't have any drivability problems I would just have them shut off the rear O2's when you get your tune done. Clogged cats will not necessarily throw a code like that, more likely it will cause misfire due to backpressure.

 

Thanks for the input! If the cat is "malfunctioning" like you said, what does that mean exactly? Would it hurt me peformance-wise?