The Scion radios have internal amplifiers. The system 10 wiring setup basically has a seperate harness that runs from the amp with one connector that plugs into fusebox in passenger side kick panel (probably for the subwoofer in the door) and then a harness that runs to the radio. This end has 2 connectors, one is the 15 pin that goes into system 10 radio and one is a connector that plugs into the connector that would plug into non-system 10 radios. Remove this connector to the system 10 harness and you probably could plug it into an amplified scion radio just like you would plug it into a stock (non system 10) celica radio from the day. In either case you will loose the door speakers.