Don't let Lexus screw you. There is no "secret ohm" kit. All the speakers in the car are 8 ohms, except for the sub, which is 16 ohm. I just recently replaced all the speakers in my 2002 sc430, and the sound sounds 100% better than their "premium, Mark Levinson" system. I kept the factory head unit, as well as the factory ML amp to run the door speakers and rear speakers. Added an Alpine amp to power my new sub. You can find way better 8 ohm speakers than what is being used in the car. I did very little modifications to make the new speakers fit. In fact, the only modification I did, was changed the door woofers (which are 6 x 9) to 6.5" pioneer woofers. I had to use a little MDF to make the speakers fit. Was very simple. I changed out the rear speakers, and they fit fine. Changed out the sub, and it fit fine...(although, I wish I could have gone with a bigger sub. Only an 8" sub would replace the old one).