Thanks CC, I may try that, in the mean time, I took the opportunity to make another one myself.
I had a fair bit of left over 200g woven and some 2mm core matting so I did a layup and cut one out that's much thinner a fraction bigger and taller with about 110% more flex that the molded plastic one.
I also made the hump more pronounced.
Took it out in some dreadful washing machine slop yesterday arvo and could not tell for sure how well it worked.
There was an excellent fullish wave this morning that really suited the Munoz so I tried it again and it does seem to have maintained the speed. But the turning is still so so.