My little guy love's bull penis as well.
My only problem is it smells so bad after he chews on it for hours. I do admit it keeps him quite entertained. He will chew it for hours without making a sound.
They are expensive but well worth the money for the amount of entertainment he gets...
I do have one question- do you let them chew on the bully stick until it is gone or throw it out? When they are small they look like a chocking hazard?