I am sure everyone who plays trumpet thinks C in b flat pitch. At least to start with. This really set me back years ago when I was in acapella choir because I was always one step off. To play the trumpet you have to "think" the note you are going to hit (preaching to the choir) and then relax and play it. When I first started playing a C trumpet this was a big obstacle because I kept thinking in b flat. Since I have started practicing again I have done 90 percent plus of my time on the C instrument. Finally I am thinking in concert pitch. I have no trouble going back down to b flat instrument. It is like slipping on a favorite old jacket. Because I like playing baroque music I am eventually wanting to get a piccolo and an Eb trumpet...wonder how hard that adjustment is going to be.