Thanks to others here I discovered www.tills.de - a KBike parts supplier in Germany.

Along with several other goodies, I bought their Bosch EV14 fuel injectors, which are an exact swap for OEM fuel injectors in my K75 and K100 RS 4-valve bikes.

I tried them in the K100RS this week. I like the result.

More power? ...not so much. But my uncalibrated hand + butt test instruments discovered what I'll call "more throttle precision". Kind of like swapping OEM rubber brake lines for braided stainless steel brake lines doesn't increase braking power, but does increase braking precision & crispness. IMHO, they are worth the $$$.

Here's a video comparing the two injectors nestled in a sub-layer of www.tills.de
https://m.youtube.com/watch?v=f8cEG4wbWyk

...NOTE: the new EV14 injector doesn't show until about 75% through the video.

Also, the www.tills.de website comes up in German, but if you click on the little blue globe towards the top right of the page, you can change to English, to USD for pricing and to all the countries of the world for shipping.