FWIW, Bose speakers in automotive applications are engineered and tuned for whatever particular vehicle they are installed in, just as the Mark Levinson system is tuned just for the specific Lexus model. Because the interior environment of each vehicle body is different, simply putting Bose speakers in your ES will not make it sound like your old Maxima. I think the ML system is outstanding personally, but I guess that is just my prefernce. My guess is that it will not be as easy as swapping one speaker for another because of the electronics behind both the Bose and ML systems.
I know this is a dumb question but, have to tried adjusting the tone controls and such for your system?
Just as a note of disclosure, I am not a fan of Bose products, but I do think their automotive applications are pretty good, especially in the Maxima. However, I think the Levinson system is a cut above.
ok, i realize that the ML is a premium system and possibly a step up from bose. however, i get minimal to no bass on sound levels less than around 30 and the system doesnt truely sound ballanced ( to my ears ) until 40. that is quite loud but frequently the level i listen to anyway. but if my wife or kids are in the car and i have the souind level at 20 or so, it is flat as hell!!! i figure some bose speakers would add the oomph that i need eventho the system might not be properly balanced. yes, i have adjusted the tone controls and that did help a little.