how do the front speakers come out?

[Dan Simoes]

I got it.  The grilles just pry up.  Good tip - the vent does NOT pry
up, only the mesh part.

Looks like 3.5" speakers in there.  What are the chances I can shoehorn
a 4"?  I have a nice pair of oddball JBL GTI 4" components (all in one
frame though) that I'd like to use.

On the rear speakers, I may try just bypassing the amps first and seeing
how they sound.