Have had this rig for about 9 months now, performing well although running a little hot. So I was looking into replacing the stock case fans to improve airflow. As I was thinking about it it turns out I know very little about good case airflow and despite reading online I could use some advice.
I've put the case on it's side as I had some issues with hard resets (thinking it was to do with my GFX not seating properly in the upright position due to a screwless bay system. I currently have:

1x Fan on the top (what would normally be the side)
1x fan on the right side behind the PSU
1x fan at the back directly facing the CPU heatsink fan which point directly at each other
The PSU fan then points directly into these two fans pointing at each other
1x air duct but space for a fan on the left side
I'm concerned the back fan and the CPU heatsink fan are conflicting with each other. I'm having a hard time telling which fans are intake and exhaust, I cant find an arrow and seeing which way tissue paper is going is not helping :(. I want to replace the stock fans anyway.
I also have a GTX 660ti with it's own (noisy) fan so keeping that as cool as possible would be a bonus. The case doesnt seem to have a spot for a front intake fan which is a bit of a let down.
One last thing is from the picture you might be able to tell that my internal cable management is poor. I don't know what to do with the considerable amount of unused cable from my PSU. I want to ensure the best airflow possible.
Temp wise my CPU under gaming load hits around 60C and the GFX card around 70-80C. Not terrible, but I think I can get it lower and increase the lifespan of my components.
Changing the case is not an option I'd like to consider at this stage. Had enough fun putting it together and then realising the heatsink mount required the motherboard to be not attached to the case first.... :(.
Would appreciate your advice chaps!