Proper Ventilation ???

I just up graded to to a hps system and have run to some heat issues. I have a 6 inch inline carbon filtered exhaust and just installed a air intake close to the light. My pictures explain the positioning better. My question is what is the ideal exhaust/ intake position within my cabinet grow. Prior to the back fan which i installed today it sat at 102 degrees. It is now only down to 99. Whats my best option??

Don't know about the best but thoughts include:

-lower the temp of the incoming air...maybe intake from an air conditioned room...
-make sure the hot exhausted air is leaving the grow area...you don't need it lingering in the room to keep up the heat...
-cool tube setup to remove heat from grow room quickly
-lower wattage on adjustable ballast so less wattage/heat is being introduced to the room
-replace or supplement (if you can lower the wattage enough) HPS light with cooler light sources like fluorescent, LED, plasma, etc

You could stand raising the humidity too. 60% for flower and 50% for veg is nice. Many pests - like spider mites - prefer hot and dry conditions so you can keep them at bay easier with cool and humid. A humidifier from walgreen's, etc can accomplish this pretty easily and cheaply. You'll hopefully get the temp down to 85F or less...