BMW E90 Deck
 

Is it possible to install an aftermarket deck on E90 and still use the buttons on the steering wheel??

Yes. Depending on the deck.

SWI-X is universal and requires you to install a remote eye. The deck needs to comes with a remote to program the frequency.

Theres a few other brand specific models also.

www.pac-audio.com

Yes you can, and yes I have done a few 335's. You do need addition parts along with a basic deck that must have front and rear preouts as well. You will need a 4 Channel amp and crossovers installed.

The only thing is, its next to impossible to retain parking sensors. But the sound system sounds 10 X better, way more bass and much clearer, which is a rare case scenario when you are integrating Aftermarket stereo to OEM Factory Amplified Sound Systems.