Hey guys, I was reading about people bypassing and plugging up the coolant lines that run through the intake manifold and TB. I know that this would help lower the incoming air temp, but i was just wondering why car manufacturers run coolant through there in the first place. Are there any negative aspects to bypassing the passages?

In florida no, anywhere where ice may form yes. Its sole purpose of running coolant through the throttle body is to de-ice it.

Only part of the intake running coolant is where the return is cast into runner 1 too.