How could I get the remote wire to turn on? I could tap into a stock amp right?

 

the stock amps only have 5volts to turn them on. you need to find a 12volt switched lead to turn on after marketamps. check the fuse panel the radio fuse should work for what you need. just tap off it.

 

if you are adding another amp and sub, you would want to get another deck. ive done this atleast 10 times: install your aftermarket unit. splice your remote turn on into 2 wires. one wire will be 12v already, use that for your new amp. on the other remote wire, take a resistor and fuse and wire them into that wire. anything from 5-10v will be fine. 12v is too risky for failure or short life, so i strongly suggest a resistor and wire. if you do take the lead from the fuse box, you will have unconstant current going to your amp. that is NOT good.