Okay...first off...about the revision changes to the Stage I.... they have not made any revision changes since they first released it...and I double checked it with the manufacture of the Turbo Tuner to confirm this....
Now I saw the post over on the e90 board... all I have to say is C'MON.... as far as the means by which they measure the underhood temp....they have three different way to do that...either an RTD, thermocouple, or as one gentlemen said, using it's own circuitry, i.e. a resistor, to measure the ambient air, which is essential using it as an RTD..... Just so you know...you were not going to find a mercury bulb thermometer in there if that is what you were looking for....
Also...the question as to why they would care what the underhood temperature is...Well lets think about this...I can think of about 17 engine operating parameters that will directly influence detonation, this doesn't even include design parameters....but we all know one of them...which is the IAT...and I'm sure if thought real hard you can figure a few more.....but did you also know that included in there is going to be engine temperature!! The engine stores a bunch of heat...and when that nice cool air rushes in...that heat want to jump ship and take a ride on cool train...
which now heats up the air after the IAS measured it.... So this external sensor is interpolating what the engine temperature could potentially be with out too much trouble....that all. Now...I WANT TO BE VERY CLEAR ON THIS...THEY ARE IN NO WAY USING THIS TEMPERATURE READING TO TUNE YOUR CAR....ALL IT IS DOING IS PROVIDING A SECONDARY SAFETY FEATURE THAT BACKS OFF BOOST TO PREVENT THE TEMPERATURE FROM RISING TOO MUCH CAUSING A SITUATION OF THE ENGINE OVERHEATING....
Lets see...what else...Oh...I do need to make a correction...I did out of error state that the Stage II TT is maxed out at 3.5psi of additional boost...and that is wrong...it's actually 4.0psi, 0.5psi higher that the Stage I...
Also I mentioned that to date there have been no failures or anything...well I guess I told a bit of a white lie...
After speaking with Split Second...he did mention that in all the years they have been selling the Original Stage I turbo tuner...the only returns they have ever received was wires pulled from the connectors...now I do want you to be clear on this...this is not in any was a design flaw, but user error...you should know that you never pull a connector or plug from the wires, but from the connector themselves...remember back when your dad would tell you, "Son you should never pull that cord out of the wall outlet by the cord itself, but from the plug..." Do you remember that...well that is the same for this, just like all the other electrical connectors on you car...