hi thanks for getting back to me. I have already butchering the car for replacing the wiring of a microswitch in the rear shell, the cable was broken. When the amplifier is fitted in the car it is usually located on the side of the driver (UK); I know this as I have two z4 and the other one has the amplifier. in the other one which is the one where I want to fit the subs, there is nothing there. I really just need to know where a) I get the audio and b) the power to supply to the amplifier. or else I need to butcher at random. then I can do.So I gather
You can add either an amp piggy back of existing internal amp just to drive the subs…or you can get an external DSP amp that takes the 4 channels from your existing head unit and then that can drive your 6 current speakers plus a pair of subs…
To improve performance you need better speakers..you say you’ve sourced all 677 speakers?
maybe if I look from the glovebox I could see if there is most or copper wire.