In context of the list of mods listed in my sig... What other mods should be done to this pup before I call it a day and smack down the hundreds on a reflash?

I just got the coupe pipe - love it and now I go over the MY350 and a bunch of folks swear by the Y pipe for the Z. Most folks here have said it's not much if any power but I want this mother to breath up high in the revs and have run out of ideas. I guess headers are a possibility but how much noise am I adding and would it almost demand a catback system - ala more noise?