I have 166 3.0 CF3 with manifold cats removed (replaced by CF2 manifolds).
Had to replace the small cats below, because they were done. One was empty and other one loose.
They got replaced by standard CATs (should be Magnaflow 54905) less then 6 months ago. Quickly they showed overheating problems (blueish color). The exhaust guy who fitted them, also said it's not normal and the car has ignition/misfire problems. An Alfa specialist said that that no way ceramic CATs should be placed there, when manifold cats are removed. The exhaust guy said that the ones are metallic, although a quick web search proves opposite.
I have no error codes about misfire or ignition problems. Now I also get P0420/30 error codes, (at least once during few days). Sometimes after heavy driving there is rough idle (at stop light) but disappears after driving, without coming back.
Any experiences or ideas? Should I replace the universal CATs with some sports/metallic 100cpsi ones? Or should I start looking for misfire/ignition problems, although there are no error codes?
Thanks in advance.