I'm pretty new, so some of my advice will be not quite hit the mark, but...

SC pulley, DCAI, modded manis, y pipe, TB are all things that can be done fairly easily (even if you are not mechanically inclined like me.

doing a custom ECU/TCU tune I would not touch, but I have heard the install process from eutocharged is pretty straight forward (I think you just send in you ecu and tcu)

I have no idea on the wavetrac LSD.