Wanting to Upgrade your Steering wheel to Multifunction but have a Aftermarket stereo like? :
Then you will most likely need one of these.
Otherwise the steering controls may not work. You need this in addition to the STMV1.
Works with most Porsches PCM of 4 or below:
• 911's 997/991,
• Cayman/Boxster 986/981
• Cayennes both gens
Bonus: It will also enable other features to work:
Ignition, parking light, vehicle speed sense, hand brake, and reverse analog signals in some vehicles.