My Dad has a 07 Z06 with an Airaid airfilter( no box) and Corser exhaust. The car has 12k miles and he drives it very little ( still learning the car- only had it since Sept of last year). The problem is sometimes he'll get a po430/435 emissions codes. He was told that possibly its a bad sensor or bad cats. Could be, I'm thinking the ECM isn't tuned for those aftermarket parts or possibly because the filter isnt in a box, the engine air intake isn't cold enough( dont know if that makes a difference or not). Anyone have any thoughts on this issue? The codes show up once in a while, Dad can clear the codes and they may not show up again for awhile.

I have an 07 ZO6. I have spent more time going through every inch of this beast and my feeling is the car, chassis, and engine are so well engineered and layed out that any mods made could post a code. Mine has 168K with no codes. With only 12K I wouldn't think ECM or bad cats would be an issue. I have a bad habit of tearing into things to see how they work and I have noticed wiring and sensors going to and coming from the "air box" if modified and wires were not replaced or not placed in the right position would create a problem.
By no means am I an expert but I'm very observant. With the Corsa exhaust I would assume an already brute sound is even more audible.
Were the mufflers put on with proper inlet and outlet passages for exhaust gas?
Since it did not through codes before the mods see if mods were installed right. Erin

Welcome to the forum. The codes you described are (as far as generic codes go)

P0430 - Catalyst System Efficiency Below Threshold (Bank 2)

P0435 - Catalyst Temperature Sensor (Bank 2)

That is indicating that the downstream 02 sensor is either giving the wrong values (the sensor or wiring is bad) or the catalytic converter is bad. An exhaust leak might also be a culprit here. What type of corsa exhaust does he have? Is it just a catback or a full system with headers? If a full system you should make sure everything is tight.

Other than that, a car with 12k should still be under warranty, right? If that's the case I'd bring it in.

Matthew