I've got a '90 Ls400, and I'm planning to upgrade from the stock Pioneer sound system by replacing the headunit, amplifier, speakers and re-doing the wiring. I"ve noticed that the stock speaker boxes we have are only 4''. The only ways I can think of fitting a larger speaker is through dremeling or getting a custom encloser for it. Does anyone have 6.5'' speakers in their setup? If yah, how did it go for ya?

 

If you want bigger speakers then you will need to build yourself some speaker baffles using MDF or birch wood. There is a lot of work envolved but its fun.