E93 Convertible - Base Stereo

[Gurj007]

Hi Guys, having done loads of reading around, Im getting really confused on how im going to proceed with my Alpine PDX 1.1000 install and my 10" Kicker s10l7 sub install in my armrest. (ive dremmeled through the back seat area already)

I will run the dvc 4ohm in series to give me an 8 ohm resistance on this 600w rms sub.

the sub is 1000w rms at 2 and 4ohm so should be 500w at 8ohm? does that sound right?

my main question is around the remote wire, where do i take the signal from as i am keeping my stock Head unit? ive run a remote wire from the trunk to behind the head unit already but no idea when to stick it next?

Will I need to get my head unit recoded or anything to install an after market amp/sub as I dont have one as standard in the base stereo?

Any help would be really appreciated!

thanks