07 civic si, stereo, aftermarket amplifier

I want to add a EQ and an aftermarket amplifier to a 2007 Honda Civic SI and a 2003 BMW 325i. Can somebody help me with the wiring of this two vehicles head units.

Also, any ideas in how to install them.

well you'll need to get a High level converter, essentially you plug it in like a speaker and then it has RCA's for the output. there are 2 channel and 4 channel models, some even include gain controls. they run between $5 and $40 dollars depending on quality, and features. for specific wiring look for a wiring diagram in the diagram section.

Im pretty sure its the same as the '06 model. And it doesnt matter if its an SI. But I do think it will differ if it has navigation. https://www.the12volt.com/installbay/forum_posts.asp~TID~68644

thanks to both of you guys.

i still need for the BMW. Is there any free website that gives out the wiring diagram for these vehicles.

if not which is the best to buy.