Yeah Z... it would seem those so called 'wild' deer are the most dangerous of 'em all. I don't know, I wanna think loud pipes help but with your pipes and the vroom, vroom examples you gave it leaves room for doubt. And I suppose cages are for the most part pretty quiet yet they encounter deer a lot.
Pipes may not be a factor in the equation at all... I still wonder though. Must be something we can do, like mount a speaker on the front that blasts out the sound of a pack of wolves on the hunt.