In addition to just playing lead, symphonic music is climbing into the upper register as well. At UNM last semester, our wind symphony performed John Adam's "Short Ride in a Fast Machine." By no means a commercial or lead piece, but it has high D concerts, and is consistently above high A concert for nearly the entire piece. (we played it on pic, which I believe is pretty standard, though the wind band arrangement calls for cornets and trumpets.) This year we are playing a piece by del Tredici called "Wartime" that also goes up to high D concert. As trumpet players as a whole get better, more is demanded of us, and one of things (BUT NOT THE ONLY THING) that we have to get better at is being consistent in the upper register. As far as building up the range, I say practice the Arban's, or whatever etude book you are comfortable with, and begin raising the excercises by half steps. This not only stretches your range, but helps your transposition. But take it easy, make them musical, not just squeaks. Keep the sound consistent all the way up. Just my two cents.