2000harvesterZ

New to the site. Got some ?s. I'm at a crossroads with the old Z. I know my cats are shot. SES has been glowing for like a year. I want high flow cats--but while I'm at it, why don't I get headers/full exhaust? While I have that going on, why don't I throw an intake manifold on? If I'm that far in, why not get heads/mild cam package. I want to stay legal (NC guys help me out) and streetable. Should I hoard all these parts away one by one till I have them all and do it all at once? What is a good starting point? Some suggestions on parts? Please show me the way...