Out of the choices you gave us, the 3" DP is the better way to go. I say 3" incase you decide later to mod more.

But I too would have to agree that a reprogrammed PCM is the better way to go. Even on a stock motor & some light mods, you don't NEED a tuned PCM, but a tuned PCM can enhance what you already have. However, before doing any kind of mods think about tune up first, if you haven't done a tune up lately, money would be best spent there. Good luck!!!