Personally I think you need to turn the fans around to blow up and out for the top panel radiator. Sure, like you have it it will be drawing cool ambient air through the rad but then it will be exhausting it into the case where it will be picked up by the 158mm radiator at the top of the back panel. That's just my thought but really, you should experiment with it both ways. It also depends on whether or not the gpu needs cooling worse than the CPU or visa versa.
The fans in your case should be arranged to create a front/bottom to back/top overall pattern of air movement. Fans that oppose one another cancel each other out and create higher inside case temps.