Just about every stock car has a feature called the cold start valve. The cold start valve is located on the bottom of the throttle body and it has two lines that run into it, one in and one out. The lines transfer coolant which in a cold start situation, helps warm up the engine faster by warming up the air in the throttle body via-coolant. In a cold climate(one that has regular temps below freezing) it has a purpose, but in summer months or a climate that doesn't have a winter of freezing temps, the cold start valve hurts hp because hot air is bad air.