Since the standard head unit has the aux button, i thought the plug was hiding behind the head unit, so it's kinda a simpe diy. But, after looked at the site of how to do that wiring diy job, I start...
It can display intake pressure, throttle position, rpm, air correction factor, VTEC solenoid signal from ECU, VTEC solenoid signal output by VAFCII (don't really get differences between this two),...
D17A2, definitely go for turbo. Won't gain much power with n/a mods, and rare parts. For intake pipe, header etc, u might look at DC sports ,AEM, or Injen.