@KrikkitTwo 's fomula thread was my reference for conversion ratio.25*15/10/8 = 4.68 when 100% techs. Not counting Hong Kong or Democracy. Hmm, after looking at the fomula, I should correct rough estimation to 4.5 because even with 50% techs(when it really matters), 25*8/10/4.5= 4.44. This is base conversion ratio, so if you want to calculate with Hong Kong, divide by 1.2, or in the case of Hong Kong and Democracy, divide by 1.56. Let me take your example of 9000 productions. 9k cogs can be 2000 gpp with 4.5 base conversion ratio. If having Hong Kong bonus, 2400 gpp. If having Democracy government, 2600 gpp. If having both of them, 3120 gpp. All these numbers are rough estimation at 50% tech or civic progress. In Democracy, 2.6k gpp is roughly 19.5k gold, assuming 7.5 gold per gpp. So Big Ben strategy or not seems more or less up to presence of Hong Kong in game.