Yesterday I did a 7-10 second pull in 5th gear starting at 2200rpms. The cooling mist gauge read 107f at the start of the pull. my water injection comes on at 4psi, for about 5 seconds of this pull. Air temp went to 106f at the end of the pull. I checked to make sure my water injection was working and it was. So, for a 10 second pull the air temp was steady. Now the air temp just after the turbo started at 130f and by the end of the 10 second pull reached 180f. But your question as far as how fast it reacts, I can't tell you. The cooling mist gauge sening unit is mounted in the UIM near the LIM. (same location as the FD air temp sender) I'm sure the sensor location has something to do with how "fast it reacts" to what the air temp really is. My SDS air temp is located before the t-body and water nozzle. That air temp increased 6degs from start to finish. Next week end I will do more highway pulls to see what the four temps are, after turbo, after intercooler-before water nozzle(SDS), at UIM-after water nozzle (collingMist) and outside air. With differant size water nozzles.

chuck