I have always rigged my Hucker 5.6mt with a Sailworks Joystick SDM 75% carbon mast and it’s been very competitive across a wide wind range. A new purchase of the Carbon Twill RDM mast from windsurfsystems, has improved acceleration, control and high end speed making the Twill far more responsive.
Sailworks has this to say about the Carbon Twill RDM. Manufactured exclusively for Sailworks by Nolimitz is our high end, high performance reduced diameter mast. It has been developed and targeted to the smaller NX, Retro and Hucker sails for high wind power riding. Constructed from 95% high modulus pre-preg carbon fiber, in a sharp-looking 2x2 carbon twill weave, for lightning fast response and crash-proof durability. The Twill masts are slightly stiffer than the Sumo, or older Backbone RDMs, so they are well suited to heavier and more aggressive riders seeking more rig tension and stability.
Its MCS, not IMCS. If it were a 430 27 IMCS is would be bloody stiff!!!!
Obviously a misprint, here's the real deal: www.sailworks.com/pdfs/Sailworks-Mast-Spex.pdf