It is, it breaks the windows on houses in the Tampa area on occasion - it has to do with the angle of the approach and etc..
Anywho, only time i recall really being "scared" as in "fearful for life" at WDW was on the TTA after it had stopped for a while and our vehicle started up again - and we came around the corner and the vehicle infront of ours was still at a dead stop and we had made it back to full speed. We knew they had bumpers and all, but weren't really sure how they worked.
It was the long straight-away going over Monsters Inc (Timekeeper at the time of the incident) and we could see it coming for a long time. Everyone in our vehicle was like "We're not stopping.. We're really not stopping.. We're doing to die! The Horror! The Horror! I'm too young to die! Why did man have to foll with mother nature! Curse you electromagnetism! AHHHH!!!"
And then like one of those dreams when you're falling out of the sky and about hit the ground but wake up in your bed, we bounced off the other vehicle and our bumpers did the mushy-bumpers thing and it was so smooth it was like two marshmallows mating. Go fig, eh?
So we all sat there, a little shocked, and waited to be evacuated.