Upon pairing a new Blackjack II phone with a 2006 GS300 there are complaints from people that my voice is extremely loud. Upon testing I found that when a person talks from the Lexus they sound overmodulated to the point of being slightly distorted. The caller sounds fine to me in the car and the speaker/volume work well. No matter what I do my voice is just extremely loud to the person on the other end of the call. I saw one TSB for a different Lexus noting a problem with the microphone where replacing the mic fixed this. I see no such TSB for the 2006 GS300.
A side note - the Motorola Razr pairs fine and sounds fine. Samsung has no firmware updates or reports of bluetooth problems on this new model phone as of yet.