Here in Wisconsin my car sits outside in the freezing cold and it is always louder once I get the car/trunk nice and toasty. I think that the lower impedance of the coil is undermined by the cold hard soft parts. I think that, unless you have soft soft parts it would be best to cool only the motor but keep the top assembly, minus the coil, the same temp as your warm cabin. But that is in sub freezing conditions as many people here have proven the opposite to be true in warmer comparisons. If I am talking out of my ass let me know, I'm here to learn.