I had some trigger issues (doubling up and such.) I moved my piezo slightly off-center.
If you can see it, there is a green dot behind the mesh head. The green dot is my 'cone' that is over the piezo. As you can see, the bass pedal strikes above the green dot, and that has given me great response. Originally, they were in the middle, and they were too sensitive. My playing style, I tend to 'bury the beater' - meaning the beater is usually against the head, and when I play the bass drum, I lift and strike, and leave the beater against the head. bad for some styles of drumming w/ acoustic drums, but, it's how I play.