Actually, that thread is about removing the DSP amp completely and making a line level pair of RCA's for your aftermarket amps (works the same way for those cars that are non-DSP like yours) You don't need to do anything with a DSP amp to get the line level signal.
You can create a line level signal to feed your amps using the line out of the tuner. There is a line level pair in the wire harness and there is an unstuffed pair that you can place pins in (and RCA's) to get a rear pair which works with the fader control. Contact El_Duderino for more info.
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