The Giorgianni 2000 is the most shallow mouthpiece you can find, and there are several that keep bouncing around on eBay, where some people find that it's not for them and resell it for a small loss.
The other one is something like the Giardinelli mouthpiece with an S cup.
I personally like the Schilke 6A4A, the smallest for standard trumpet in their line.
I suggest something like a Schilke 14A4A or 13A4A which gives you the best range and quality of sound, but DO NOT OVER USE THEM! I have talked to people over the years and they say that using the wrong mouthpiece with too small a cup size will ruin your embouchure. So treat it like candy and don't overdose.
The best trumpet mouthpiece to hit high notes is the one that you are comfortable with for the long run.