If the MBP has the NVidia chip, you'll have to select an SSD that does not have problems with this chip. The name of the SATA chip should appear in the top middle portion of the window. To find out if the computer has this chip, press the Apple Logo in the left top corner, press 'About This Mac', press 'System Report', select 'SATA' from the left dock under the Hardware heading. People have reported issues with the NVidia MCP79 SATA chips in this MBP and certain SSD's.

So if you just need one SSD and you put it in where the HDD is, you're OK. PRE-2011 models can utilize a 6G drive in the optical bay, but will do so at a reduced 3G (3Gb/s) speed. If your OWC Data Doubler bundle comes with a 6G drive, you should ONLY install that drive in the main drive bay and utilize the Data Doubler to re-task your existing drive or install a new 3G SSD or HDD in the optical bay. Testing has demonstrated that Apple factory hardware does not reliably support a 6G (6Gb/s) Solid State Drive or Hard Disk Drive in the optical bay of 2011 MacBook Pros (ModeI ID8,1 8,2 8,3). There have been several threads (going on at the same time) about putting an SSD in MBP's of this vintage.

Solid state drive for macbook pro 2011