To the issue of the trunk spoiler, do a before and after with your scan gauge and let us know
I don't have one. Although, on TeamZX2, David Gettle claims he gained mpg with his massive Ricer wing
To the issue of the ZX2 knock sensor. Before TeamZX2 crashed, there was a dyno and datalog showing how the knock sensor was always pulling timing, anywhere from 3-6* all the way from bottom to top rpm. The before dyno has all sorts of dips in the curve, the after was smooth and 6 hp more from 3K up to redline. Before I pulled mine, I always had this surging over 30mph. I just thought it was normal. Drove more than 100,000 miles that way. After I pulled it the surge went away and it ran sooooooo much better. I haven't had any ignition timing related pinging, have had some vacuum leaks that I thought were knock sensor pulling related. The knock sensor on the ZX2 is useless. The ZX2 is timing starved, thus the addition of a 5.6K ohm sensor on the IAT makes such a big difference in mpg's for most folks. I saw around 2mpg better from that.
Oh yea, I tried high test and it still pulled timing.
Yes, excessive hot air could cause troubles.