Deer whistles don't work.
As to loud pipes, I work nights.... I leave work at midnight-thirty or so, and I already know I'm gonna see deer on the way home. I look for them and take it slow.
If I see them and they are too close for comfort, I pull in the clutch and blip the throttle a few times. So far, that seems to be enough to spook them and send them away from me.
It's not a fool-proof method, but I have to think that blipping the throttle with stock pipes would not have the same effect. Deer are much more alert to sounds than they are to lights, even the domesticated ones around here.
I've driven all the way home without seeing any, only to find 3 or 4 standing in my yard as I reach home, and I live in an older housing plan - with homes all around.
