My mid 2013 13" MacBook Air has a 250 gig Samsung SSD inside it, whereas for my late 2012 Mac Mini, I replaced the slow, 5400 rpm 1 TB drive with a 256 gig Samsung SSD Pro drive. I believe the Samsung SSD inside the Air is the "EVO" variety, instead of the "Pro" variety inside my Mac Mini. I thus suspect that Cory is correct, in that you will not see much speed improvement (if any) in replacing the 512 gig SSD inside your machine.
Can you tell us the specific MacBook Pro model you have (13", 15", Retina, etc.)? Also, do you know what specific model SSD drive you have now? And, have you done any cleanup/maintenance on the present SSD?