Membership minus and ''Quasi Article-5'' – The real association mechanisms

I would like to start by saying that I have strong doubts about the direct link between democracy and economic performance. Just have a look at India, a democracy with incredible economic growth. However, It is very likely that those who earn their $400 per day would never see a ballot box in their lives. China, with four times the pro-capita income of India, is not a democracy – they would never even accuse themselves to be a democracy. So I am  not sure what the link between economic growth and democratic systems is.