I had a Pacbrake installed on my 04 and was not happy with the noise the compressor made. So I sent an e mail to Pacbrake asking if there was a solution to this. They in turn sent to me a new free mounting kit for the compressor. The kit allows the brake to be installed on the top of the motor. The dealer from whom I got the brake reinstalled the compressor at no charge. Now the nosie is gone. What a difference.