Hi Waltgill,
I've found that using different types of chilli's in those hot curries bring out the best. I always use a "TRS Very hot chili powder", but I also use a combination of fresh chilli's such as Scotch bonnets. (I prefer Habenaro but they're kinda hard to find here").
I also will use dried red chilli's as well. I normally soak them for around 20 minutes in a little hot water to soften them. (Don't forget to add that small amount of hot water to your curry), then chop up the softened chili or even just slice it down the middle and put it in.
What you'll end up with is a mouth watering sensation as the chili hits the palate, but then climbs to a crescendo as you chew the food, and once you have swallowed a heat that remains in your mouth until the next wave.
Give it a try and experiment

...........