Start on the Audio Sub Forum
and read this first
BMW stereo types
and the other sub forums are here
Jl xd600/6 is the standard drop in for the Hi Fi system
why it has 6 channels(same as Hi Fi) , It fits in the OEM position ,
Its high quality and very efficient , It has the balanced Inputs that
match the balanced outputs of the Head Unit and fight any kind of
random noise. Get a Technic Harness to avoid any kind of wire cutting
and make things easy(The p&p factor). It is a lot of power for the stock speakers
but people have not been reporting fryed speakers so far. Door speaker
gain setting must be kept to a minimum.
With just the amp you will get better base and cleaner highs .
The front door and speaker s should be changed the favored speakers
are Morel's for the doors and Jehnert for the floors for maximum fidelity.
There are cheaper speaker that will still improve things quite a bit like
Rainbows for the doors and SWS-8's for the floors.