Originally Posted by ctuna
Technic makes a plug and play harness
This means you don't have to cut any wires .
It plugs right into the amp plug/wiring harness where the old Hi Fi amp goes.
It also buffers the turn on signal with a relay.
Plugs right into the amp connector for Hi Fi he also has other
types for the other systems. Also everything is labeled.
There are multiple pictures of it in that link he gave you for his sisters
upgrade, with only tweeters and a XD added.
Thanks for posting this! This is my third post so I can PM and/or start my own thread. I am looking to upgrade my 2008 335i e90 with Top HiFi and dying to get started.