1999 BMW 328 sub

I have a 1999 (E46) 328i with the HK system. I would like to install 2 10' subs in the trunk. What do I need to do. I noticed right now there appears to be a small factory subs would the factory amp have enough output for 2 10" subs? If not how would I go about by-bassing the rear factory amp and installing a new amp? I also need the wire diagram, I looked up the chart in the stereo info but it only shows the wire color code from the head unit not the color code from the amp (if this makes sense). Thank you

No need to bypass the factory amp at all.  You will need a new amp and a line out converter.  Connect a line out converter (available at your stereo shop) to the wires feeding the factory subs (which I'd also remove).  Then run your rca's from there to your new amp.  You can "pop" the subs for proper polarity.  If you're not sure what that means, read the sticky labelled "how to figure out stereo wiring".My ex once told me I have a perfect face for radio.