I have been trying to mod my YAMAHA 6335 trumpet with aftermarket parts, just like some people do with their cars. Unfortunately, most of the products are for makes like that of Bach and Schilke, and without thorough knowledge of the dimension of the valve cases and screw pitch, buying a part intended for another make which works on your trumpet is hit-and-miss at best.
But these heavy caps do fit on my trumpet, and they do change its playing characteristics quite conspicuously.
They add quite a bit of a substance to the sound of my trumpet, which also means more projection and good stability across the range.
Arguably, they add a little bit of a "Vincent Bach" characteristic to my YAMAHA - placebo effect as you may argue, but a positive change of the projecting quality is pretty affirmative in my case.
