It's tolerable...as long as the comps are bolted down pretty well, it's not too bad. They're probably the quietest compressors I've seen so far. I've usually got the stereo going, so I don't hear them much anyway....I just watch for my volt meter to drop when they kick on...lowhombre said:how loud is the 450 comp inside the blaze, how loud do you think it will be inside an reg cab s10???:boobies: