Basically there are 2 models of superdrives.
one is the Hitachi-LG model and the other is the Matsushita (sp?)/Panasonic model.
the panasonic model in my experience has always been the louder drive during the drive's initialization on boot up. the HT-LG is quiet. its really 50/50 on what drive you get. This is coming from someone who has had the LG first, then replaced with a Panasonic. The Panasonic on my first MBP was also louder.