Eventually.... Bob Reeves 40C (slightly smaller diameter than a Bach 17C, but a fraction deeper and more V shaped cup) with a Reeves 40S when I want more zing.
But these are probably a bit small for most people, so I'm not sure whether I'd necessarily recommend them if you see what I mean?
Unfortunately no mouthpieces give us free notes up top, only practice and correct technique does that.
Some mouthpieces make it easier to last up there (stamina) and/or make the slots more rigid... The payoff is a much more direct and piercing tone which doesn't really fit brass bands for most playing, along with harder work playing quietly.
There are so many to choose from, I found it much more difficult to find mouthpieces that work for me for soprano compared to Bb cornet. I'm currently using a Curry custom mouthpiece on soprano, EC 5S is the model. I had previously used a Bach 12C and also an Alliance BVT which I really like and may use again at some point. Keith, I have a spare Warburton 8MC top that is in new condition that may be worth a try. Warburton are good mouthpieces, just so many options to choose from. I was fortunate that I was in a music store in Canada who had the full range of tops and backbores so I could try them out and select one that I liked. It becomes an expensive hobby buying mouthpieces. . .