Updated: Jul 10
Three of the best stretches for the piriformis. Keep in mind if the piriformis is over facilitated that glute max is probably inhibited and not firing in the correct sequence. The deep 6 (probably the IT Band, TFL, vastus lateralis, and lateral aspect of the gastroc, as well) are over facilitated.
If you are going to stretch the piriformis to quiet it down, strengthen the glute max by doing some glute bridges following the stretch, otherwise you have done very little to correct.