This problem can be solved without any engineering knowledge. Just common sense and empirical testing. Seems to me everyone's gotten off topic and completely skipped over one of the most important details. This is an E36 install.

The center console of the E36 has a double vent just above where the stock radio (or empeg in this case) is mounted.

Image from my install thread: http://empegbbs.com/ubbthreads/showflat.php?Cat=0&Board=install&Number=241048



Now, something you may consider convenient, annoying or just plain confusing, is the presence of a temperature dial just below the center vent (it's the dial on the left between empeg and vent). Most every other car I've ever seen has only a control to modulate air flow for a center vent (the dial on the right). This dial allows you to modulate (quickly) the effectiive temperature of the air coming into the cabin regardless of the thermostat setting.

If you have your thrmostat (either or both temperature zones) set high (hot) you can still dial the center vent to a center position to get neutral air or to blue for cooler air. The air duct behind the empeg is strictly for the center vent. Experiment with different dial settings and flow control (to meter the effect of the chosen temperature on the cabin temp). I normally leave mine set to center, but in the winter (if it's cold - I live in Canada near Toronto) I will dial it to max heat. I've never had a problem with empeg overheating in this car either way, but obviously YMMV.

I'm also running a 100GB Seagate drive and 30GB Fujitsu - can't say for sure, but some drive make/models may very well run hotter than others.

Bruno