I ride with a couple of cyclists with piriformis syndrome. Yes, stretched out is good. Until just a few years ago, I could still remember the taste of toe from when I was very young. So one of my stretches is to attempt to get that taste again. I'm only about 6" away, but I doubt I'll ever quite get there.

My morning stretches: IT Band pain (during ride)
They're also good after 100k or so on a hard ride.

Stack.com is a fascinating source of workout and stretching ideas. My guess is that deep barbell squats are good for piriformis. They make me sore in that area anyway, so that's good. Good squat tutorial: A familiar chant around the squat rack: "elbows, elbows, elbows."