Glen, the chillis I used are not the hottest type, thin, 2-3 cm long (Grand Continental brand), you lose a bit getting the seeds out and they aren't as hot as the Italian tiny pepperoncino chillis. You could also use the bigger, milder ones as well/instead. I did add about 7 small fresh/frozen chillis from my garden last season as well. It was just right for three of the 6 people eating it, and copious amounts of water and/or milk were consumed by the others. There were other dishes as well - a Thai-style beef salad (deliberately without much chilli though) and stir-fried vegetables with soy and oyster sauce.
A really hot curry breaks out a good sweat on the top of my head, this one produced a mild sheen. One person did mention "still bleeding under the eyes" 10 minutes later though.
I cooked this on the BBQ wok-burner outside, I was sneezing a bit when the wind was blowing in the wrong direction.
If cooking inside, set the exhaust fan on max.
The red-drinkers drank a Willespie MR Shiraz 99 and a Small Gully Barossa Shiraz 2001 (an ex-Wine Orb auction buy and great value at $11) with the food, both a good match.