(Keep in mind that every stat is a same, this is more like a buff though it can be changed)
Copper Heat Sink
-Cooldown time when overheating: -25% (is it too much?)
Aluminum Heat Sink
-5% heat build-up (total -20%) in frozen and hot (total +10%) enviroment
Pyrolytic Graphite Heat Sink
-Heat dissipation when not firing: +10% (a bit too less?)
Beryllium Oxide Heat Sink
-Heat build-up when using Overdrive: -10%
Cubic Boron Arsenide Heat Sink
Make newbie wonder why your weapon is not overheated yet.