There seems to be this belief now that a positive air pressure is helping with heat management and the thing is this , the best thing for heat management in a computer case is to remove the heat from the inside of the case pure and simple.
By removing the heat from the inside of the case then the parts that are cooled by air/fans will get cooler air to blow onto the component. What good is it to have more fans blowing air into the case and one blowing out , that's keeping the heat inside the case.
With the fans that you have in your case you should have the front fan as intake the rear and top fans as exaust.
Well you have two fans in and two fans out it should work fine.
I use two fans in on the front of the case and two fans on the back of the case but one of my rads is attached to the back of the case with 5" standoff's between the case and the rad itself with more fans on the rad in a pull position from the rad.
What you are doing is the same kind of setup you might consider putting the rad off the top of the case with some standoff's and more fans on the rad itself that way you’re not pulling hot air through your rad to cool your water.