If the picture is anything to go with it might be even simpler than the booster plug. I would guess that it's either
- A 3K@25C B=3950 Thermistor which is essentially identical to the original and just moves the air temp reading away from the engine
- A 5K@25C B=3950 Thermistor which would drop the temperature the ECU thinks it's at by ~11C
If it's the latter, then it's trying to do a similar thing as a booster plug (but bypassing the stock thermistor entirely).
I just ordered the components and will test in a couple of weeks when they arrive. I think the connector they use isn't quite the right one either, it'll fit but won't latch. Total cost is less than $5
.