I wouldn't worry about the WEI. I'm getting a 5.9 as well with a V. Raptor and it really doesn't matter much by way of every day performance. Windows 7 is set up to only give above a 5.9 with solid state drives (for the most part). If you want more performance and better numbers, go with a SSD. Otherwise than that, I'd say you are fine, as the WD Black (that's what you have, correct?) is a good performing drive, regardless of what Windows says.