sndlover

an 09 ES350 w/NAV and I understand your interest to improve its sound system. Changing the sub by adding an 8" or an enclosured 12" driver with amp is a good start but it does not give the clarity, best frequency curve or wide image that this system needs. Changing tweeters and other drivers might help on loud passages but for a sound system as expensive as this, I wouldn't expect big improvements and it is not simple to substitute all the 14 drivers. My approach would be to get one of those OEM integration processors such as the Alpine PXE-H660 that will improve the sound the way you want it, adding one of those multi-channel amp. No speakers need to be replaced. Check on the WEB for the best processor and amp that fit your budget. I'll do the same as soon as I have the cash and the time for it.