like i said, it depends on the amp and the volume level. the new digital hd amps will stay cooler longer allowing you to play longer louder before hitting the thermal protection, if airspace is an issue. also computer fans do wonders in these tight situations. my computer is a bit overkill and needs some good cooling and my fans are about 25db. at this level i cant hear them from 8 feet away. given the truck engine is running and you are moving down the road, you could go with a more productive fan, or keep quiet ones so you dont hear them at all.