Just finished painting the first 10 lambda relays. I tested with a 4 amp load (I tested lambda current a bout 2 amps) so power (heat produced) is 0.10 watts. So basically my lambda relay will run at ambient temperature. This is plug and play but only to be used for the lambda relay socket (yellow socket). I'm pricing the lambda relay at $69 shipped to US locations.
Now the relays always on, RPM, lambda and AUX relays are the ones producing the most heat in the relay compartment. I run my standard solid state relays for the AUX relays but they do no have the large power and ground pins.