this is the problem with my cab. my intake and exhaust are up agains the wall about 1.75" away. and the exhaust fans are just blowing straigh into the wall. and i belive some of that hot air is being forced down and being sucked back into the intakte. though yes we all know heat rises. im going to put some dryer exhaust piping on the intake and rout it around and in front so it gets "fresh" air.
edit:
added some ducting. you can see i had an outline for another 120mm fan and i think i will add another one, but this one will be on the side