Check it... This mod definatley works. Upshifts are much harder and you lose much less RPMs between shifts. You should install a trans cooler if you plan on using this mod often, as when the IAT is deactivated the trans fluid pressure is increased and heat builds up faster reducing the life of your transmission.
Not sure which one is which, but you should cut the incoming wire to the IAT if you are using a switch with a light, so that the light does not dim when the resistance goes up in the IAT. Transversley, if the light dimming does not bother you, using the return wire from the IAT can give you a general idea of the air temp goin through the VAF, ie, the light on switch being dimmer or brighter...
Adding the switch(before or after IAT) also increases resistance slightly making the ecu think that air temperature is slightly lower than it actually is while IAT is still enabled. I noticed the difference the first time I drove it after the mod.