The second thing that really stood out was the fact that he played the ole Turpin and the call that Neil made just like he played his own....Hmmm....so, I've spent a lot of time the last couple of days with a trumpet attached to my lips searching for that yelp
I noticed the same thing Kenny, I had heard that it might be his mouthpiece, but apparently not. I too have been messing with my KP trumpet trying to get that raspy yelp, I have found enough to make me happy for the time being. For me it is hand placement/shape over the barrel and lip/mouth/air tension if that makes sense. Anyway, fun to mess around with different ways to play these things.