Really hot is according to your taste preference.
To me they are about Jalapeno hot in general.
You might have one that is hotter.
Maybe try them less ripe to see if they are more to your heat/taste likes.
I'd start with when they just start to turn to see what you like.
I'd go with The riper the better for taste and heat in general..
Try early green and if it isn't the taste/heat you want go up from there.
Let then b go a while longer.
You'll find out what taste and heat you like, eventuallty.

Thanks Smokemaster.