That's going to be a problem for CA I/M testing unless
1) The kit has a CARB E.O. number - meaning its certified
2) The upgrade looks enough like stock to fool the tech
3) The tech is stupid, doesn't care, or you pay him/her off
One big problem is if you get caught, you run the risk of winding up on the "Black List" whereby you have to go henceforth to a referee station for all your I/M tests. No way you can fool around with those guys.