are there viable options to replace the Nakamichi radio in a 1999 LS400, also the amp and speakers? i live in detroit

 

Search the LS400 forums. You can easily buy a wiring harness, DIN adapater plate, and install any DIN stereo.

As far as amps, the possibilities are limitless.. You have to be a little more specific. But you could get by with just replacing the head unit with an aftermarket din, and use its internal amp to power all 4 speakers. You will however lose the sub.