Why are you not measuring the temperature on the move? I got a little thermometer off ebay, that cost a few quid and has a probe on a wire that can fed into the engine bay.
Obviously as a scientist, I would look at both temperatures at standstill and whilst running, when colder more dense air is being sourced from outside.
I bought a grille from http://www.grille-tech.com
Cost me £40.00 for the standard supra one, fits with some zip-ties (which is only temporary whilst I source some long bolts)
I then spent £15.00 and bought a pipercross, cold air feed, from ebay - which includes the intake trumpets. Drilled holes in them and fitted them to the grille and offered the whole thing up: after a bit of faffing about it all fitted well.
Now then, as I am using an N/A supra all the plastic work was removed (where you would normally have intercooler pipes) I fed the flexi-pipe into the engine bay.
There has been a change in performance, I have been using the Injen Intake for a while so I could justify the improvement. The throttle is a little snappier and it seems to pull better.