Some may know that I was having a problem with the formulas in the "selecting turbo size" thread. I now know what the error is. I hope Projekteg or some other mod will edit the thread to compensate for the error.

Instead of multiplying the quanity of (P2/P1) by .283, it is supposed to be that quanity raised to the .283 power.

So...
T2=T1[(P2/P1)^.283] is what it should be for those who care.