Based on the design of the Hikari the “driver” modules they just provide fan control and voltage conversion/regulation. The “driver” chassis design does not indicate that there will be substantial heat dissipation needed. Also this is a low voltage DC system I doubt there is enough power dissipation to create a significant heat source. Especially when you consider the volume of the headlight assembly and that the bulb itself has a well designed fan/heat sink. Since the headlight assembly is subjected to engine bay heat leaving the back open may not present much of a temperature drop as the is no cool air source near by. To understand the pros/cons we really need to understand the running temp of the bulb assembly, temp of the “driver” and local ambient temps.
I will try to get some heat measurements of the bulb and driver tonight. I personally like having the headlight assembly sealed up from the outside environments.
The drivers for the DSWO's I got for the fogs (and now have sitting after a full refund for going out of synch), well the driver modules got hot as hell... but likely because they were garbage to begin with. BUT, the oEdRo's I'm running for headlights right now don't seem to get as hot and I have them tucked away in the housing, with no rear covers. I'll have to consider how hot the MAXGTRS get, that's something we'll have [MENTION=3563]TyphoonFiST[/MENTION] maybe check for me... I'd love to get the Hikari and be done with it, but for 1/3rd the price I'm likely going to have to settle for the MAXGTRS, if I even switch in the near future... With LED not taking a lot of power there is still heat loss involved in the conversion, but ifthe total wattage pull is less than halogen we should be fine anyway, even if they are more sensitive to dimming with heat.