1. Biogas generates twice as much heat as it should. If also generates twice as much EU if you use liquid firebox + stirling generator.
2. Speed boost from Coffee does not stack (yes I use hot coffee with milk and sugar). No matter now many mugs of coffee I drink the speed boost is always "Speed I". It even says "Speed II" when "Speed III" as I keep drinking coffee but my FOV changes only once (yes I have my dynamic FOV enabled) and it always works as "Speed I". The haste boost and the duration is fine