Can you replace the old navigation in a 2004 sc430 with something else? If so what?

 

Maybe there is tons of good reading on it though the search button will help you find the answers you need.

 

2004 has Gen 3 Nav. It can be easily replaced (plug and play) with a Toyota or Lexus Gen 4 Nav unit easily found on ebay. Use search to see details. Gen4 gives you access to slightly newer maps (maybe 2015 is the last update?) and it runs a little faster with a bit better graphics but it is an incremental advance, not huge by any means - there is no easy way to get to latest Gen Nav.