L20 or Via Aqua 1300 for TC4 Rev 2??

Hello everyone....
I just got this waterblock this week, and I was playing with some, with different configurations, but I am still getting pretty ugly result from this block. So after I tried various settings, I came up with a question, is it because of the copper coil in the waterblock, therefore, I need a pretty powerful pump (ie 3xx GPH) in order to get a better result?

thanks everyone.