I want to buy DC Sport headers for my ej1, but i want to make it completely legal and want it to pass smog with the headers on, what do i need to do or buy in order for the car with headers to pass smog? or will the headers bolt straight onto my old cat?

 

Header. One. Not two. We only have one bank of exhaust ports.

That said, as long as you buy a legitimate one that is CARB certified, and as long as your engine is in healthy running condition, you shouldn't have any problems. Also remember that you won't actually gain anything - it's nothing but a "bling" piece.