Order of install
2) headers AND y-pipe...you cant do one without the other (unless you are doing shorty headers)
Now, if you are by any chance thinking of doing true duals, do the headers AND the exhaust at the same time because its a custom build (exhaust).
The coated y-pipe probubly won't give you more HP but it will keep it from rusting (longer life). I personally just painted mine (no point spending the extra $$ here in AZ's dry climate
).
). Then ask if the catback you have/want to use/etc will work with that header/y-pipe setup.

