i have a 2006 bmw 325i (e90) which has the battery in the trunk. i want to know how i can connect my 2 12's and 2 amps to the stock headunit? or would i have to buy a new headunit such as pioneer alpine etc.??? plz if any1 has a BMW and has connected a system to it, let me know how.

Your better off buying a new head unit anyways..

What do you mean by "system"

Do you have the 12's and the amp?

If you have a 2006 you more than likely have the "I drive" I would assume?

If so the amp is located on the driver side of the car. This is a 5 series but the 3 is almost identical. If you haven't done many systems before I would recomend having an experienced installer do the install. All you will need is some line level adaptors to to attach your rca's to your factory speaker wiring unless your amps high level inputs. Remote can be found in the rear passenger side using a green ignition wire. However if you want the amps to stay on untill you push the key you need to catch the keysense wire up front and use a relay because accesory for the factory headunit is databus. If you run any wiring up front the seatis fairly easy to remove just be carfull of the seatbelt locking mechanism wires. The are attached to the same bolts that hold the back of the seat down. If you don't have the fold down option then you will have to use a small screw driver to open the latches holding the top of the back of the seat.