I live in the United States and go to Indian restaurants every now and then. I like hot and spicy, but the Indians don't take me seriously. They usually have a range of heat starting with 1 (mild) and advancing to 10 (hottest). I tell them to bring me an 11. What I get is certainly hot, but not particularly challenging. I know hotter is possible because many years ago I got a vindaloo in Cardiff, and it near took my head off. Perhaps it helps to have a historical connection to India for the natives to take you seriously.