2000 lexus gs 400 question

hello all,

i am new here, just found this site today. wow what a big forum!

here is my question....

i have a 2000 lexus gs400 with the nakamichi sound system. i want to replace just the speakers, but i can't seem to find too much info on what will work. can anyone point me in the right direction? vehicle has 7 speakers i believe. components in the front doors, a speaker in each r. door and a free air sub in the rear. iirc somebody from lexus told me the speakers are made by pioneer and the rest of the system is nakamichi.

help?????