How do i improve my hot and spicy chicken breast recipes so that the heat isn't an after taste?
You need chili. Most of your heat comes from black pepper, which is different from the heat in chili, and isn't as strong or long lasting. Chili heat is immediate, persistent, lasts and builds up as you eat more so that's where you want to go. The thing is to control the heat by modifying the strength and amount of the chili you use. There's so much variation in chilis, from mild to tonsil-destruction, you just need to find a one you like and add the right amount. Some experimentation is in order.

One easy step would be to add some chili powder to your marinade and see how you like it. A more immediate chili may come from fresh chili in a salsa or barbecue sauce that goes on the side. Marinades only penetrate a little way, all the flavor is on the outside, a sauce would give you heat throughout, and fresh chili tends to be a more immediate flavor. There are plenty of mild varieties to try.