Essentially if you're going for ease of installation without wiring harness splicing and adding a new amplifier, a MOST adapter is what you'd be looking for. Not the cheapest method, but fairly plug & play.
BergvillFX ISO Audio Power Harness for MOST
I'm not 100% certain that this will work with the 9x7 chassis cars, but you could ask Tore Bergvill to clarify.
Boxster
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Threaded Mode
