Hi,
I am using heatsinks on the SIDs too.
I noticed that they get really hot so bought some 28DIP format heatsinks and a thermal conductive biadhesive tape ( I found AKASA but I think there are others too )
I made some drills in the bottom of the case and used a fan taking supply from J4 GND - 9V W/O any resistor
Regards
Antix