I have a non RF navi and am planning on upgrading my speakers and adding an amplifier sometime soon

what I am trying to get information on is
is the signal wiring for an amplifier ran to the drivers seat already or do I need to add it ?
If not what exactly do I need? Ex: rca / harness / splice from speaker wires ?
Speaker fit depth as is stock

I'd like to have everything ready before I take stuff apart

I couldn't seem to find any threads about a NON RF system having a amplifier added
and a speaker upgrade while keeping the factory navi

if anyone else has done this any information any details would be appreciated thank you