I have some logs posted under self tuning section, short version is my trial and errors data say get a good IC first if you are in a hot humid climate. Then downpipe. I currently run Cobb IC, 2J DP, Mountune Intake and Cobb S3 tune 93 gas with OEM exhaust. Plenty of juice for right now. My data show this setup does not benefit at all from the 3" cat back I had on, so I removed it, much stealthier now.
Doing your own DP install is difficult even with all the good guide info on this forum, but once you do it, future work is a lot easier, lots of little tricks learned by doing it help. Being rid of OEM cat heat shield helps too. Be sure to keep OEM exhaust manifold heat shield, I tried leaving it off and heat hurt performance, so back on it went...