Hi Uwe, I've been using the MFC Carbon with Freeride and Race foils for two years. Can't fault them, using with 4.0 to 8.6 on 80cm/120l slalom board and 100cm/167l Formula board. Have the shims, but don't use them, everything works fine.

What would you like to know?

Like I said, I don't use the shims. A long time since I used the shims, and I mustn't have found them an advantage, otherwise I guess I would still be using them. I think I recall them not assisting early flight, and perhaps providing too much lift when flying.

It sounds like a general foiling technique thing you need to work on, correcting back foot / front foot pressure, and sail sheeting. Perhaps adjust mast (sail) position and footstraps. If you find it unstable above a certain height, the easy solution is to avoid getting too high. Have you compared with other foils?

I am really enjoying this foil, and can't speak highly enough of it. Perfectly crafted, 100% carbon, light, stiff, stable, fast and manoeuvrable. I'd encourage you to persevere, adjust your technique, and settings, and go shimless.