From what I've read the "TB coolent bypass mod" should only be done by people that live in the southern states (never gets below freezing) because the purpose of having the coolent flow through the TB is to keep it from "icing up" (possibly freezing in position) ,obviously causing extream driving problems.
Leaving it stock (Coolent flowing past the TB) incool weather kind of defeats your CAI (if you have one) by preheating the incoming air and in hot weather it really doesn't affect anything at all (since the incoming air is already too hot for the coolent temperature to affect it).
So in effect if you drive anywhere that it gets cold leave it alone, if you don't then the "TB coolent bypass mod" may add 3-5 HP in cool weather driving only.