Ok I'm very new to the whole engine management/tuning thing and I just picked up a new/used Evo and its not stock. Its been tuned by a very reliable tuner here in Europe, and I'm not messing with it. I just want to know what I'm looking at and if I got it right. Through searching on the forum and other places this is what I've come up with. Let me know if its right or wrong.

Its got a Apexi AVC-R boost controler. Basicly my electronic boost control. Next up hidden in the glove box was the FC Commander. Which replaces my stock ECU. Its the brain of the tune and where all the "magic" happens. And to follow up its got the Defi Link control Unit which is the "hub" for everything. Like I said I'm not messing with anything. I just want to know what all everything does.

Are there any other places on the web where I can do more reading on engine management/tuning? Also with this set up will I be able to have two different maps? Basicly a High or low/valet setting?