Instead of going for a new MacBook Pro with retina and I decided to upgrade my early 2011 13" MacBook Pro with a 256 GB SSD. Might as well save a few bucks. After installing the SSD, I'm getting about 330 write speed and 500 read using Black Magic. Does this sound right? I thought the SSD should be reading and writing at 500. By the way, the SSD is a Crucial MX100. Thanks.