Haa haa do you know I probably was, I knew there must be another reason other than me for being soooooo slow.
I did buy some and also some double springs to stop valve bounce but never fitted them before I stopped racing.
Reading this thread made me go and look at my very old web page,
www.avnet.co.uk/raw/beetle.cup
it's had over 100 thousand hits but is 10 years old. Blimey
The details page shows the car as I sold it to the Portuguese chap. I'd love to know if he is still racing it. Funny but I remember it as being very clean and pristine, funny how your stanards change.