Heyy i just picked up a 2010 lancer Se and i was wanting to do the sound system. I was just wondering if and what i would need to hook up a aftermarket deck i know i need the Dash kit - http://www.autotoys.com/x/product.php?productid=26073. But what else will i need to keep my handsfree and steering wheel controls ?

the other parts of the sound system seem easy enough to install so (aka) speaker, amp's, sub.

 

A harness adapter to mate to the factory stereo harness. This is so you can solder and heat shrink all your wiring to the new head unit on the bench then simply connect to the factory connector you will remove from the factory head unit. Also for hands free and steering controls I believe there is an aftermarket wiring harness (may be the same brand as the new head unit)
Just throw up a search as a lot of people have already done this.
Cheers!

 

Get the PAC SWI (steering wheel interface) to keep the controls

You get hands-free bluetooth now through the deck. Make sure it has it.