16GB will work if used with 2 8GB modules.
You can even install up to 2133Mhz ddr3l RAM and the system will utilize the 2133Mhz.
many threads on the subject.
I belive Kingston hyperx ddr3l SODIMM are popular and works
I wish you best of luck with your 2011 MacBook Pro. Are you aware of the gpu issues on that particular model. I'm dealing with it right now.
Also 16 gb ram is podsible