This can be a tough one as I don't know you're heat level of enjoyment. But, you can try this one to get you started.
Simmer 1 fresh diced jalapeno w/or w/o seeds, 1/2 onion, 2 cloves of garlic. When they cook down, puree and strain the contents and add to your fav BBQ sauce. You can adjust it from here on. I can't see you making a large batch, and then not liking it. If it's too hot, add a very small amount of honey to bring it down. If it's not hot enough, add more jalapeno or even fresh diced Serrano. like I said, it's a tough call off the cuff. It's all good my friend.