chili chocolate stout

So I'm making a chili chocolate stout. I added 3/4 cup od cocoa powdr at the very end of the boil and it's currently in the primary. I want the beer to have a very subtle bite to it from the chili. I wondering if anyone has previous experience experimenting with spice. I was toying with the idea of adding dried chili flakes when I move the batch to the secondary. Any ideas on how much to use, or if there is something better to use than dried chili flakes.

cheers

made a small beer with some leftover grains and added roughly 1.5 tbsp to the 1gl boil, and that was way too much. it tasted spot on delicious, but you'd have to take your sips about 5 minutes apart to let your tongue and throat cool down. it's aged about a month and a half now and is getting better.
i added some chipotle powder to an irish red at bottling, and it came out pretty good because i could test and control the amount and balance it out with the (nearly) finished beer.
i'd suggest starting low and adding more during the various stages.