The Juice Box?
The Juice Box

You can make your own juice box too
Radio shack sells cases just like hte one shown for enclosing circuits... get that, print your own label, then bring 2 wires out of it connected to a resistor inside (be sure to glue the lid on so it can't be dsiassembled ... wouldn't want people to know the secret of hp hehe) , then a connected on the end to plug into the IAT wire and done 
You can use your Intake Air Temperature sensor or your Coolant Temperature Sensor
However I would advice against it... backgrond info on why this works on *some* cars
The PCM has several tables that can add or remove timing based on Incoming Air Temp or Engine Coolant Temp (IAT or ECT)
Attached are examples of each... when the IAT is hot ( > 100*) the PCM will start pulling timing , since hot air = less dense than cold air, plus hot air is a warmer intake charge so greater chance of pre-ignition/detonation
These "modules" aka resistors, force the PCM to read a constant temp, the page says you can use ECT or IAT ... ECT is just stupid... too many things in the PCM depend on this value, the IAT sensor is best left as is but if you *really* want to trick it you just need a resistor ...



