iSonic 133 or 144

Hi all,
One question
The description of the iSonic says:

The iSonic 133 W85 and 144 W85 are two all new models designed for the ultimate in lightwind slalom performance following the PWA's 2008 85cm width limit. The 133 for lightweights, the 144 for heavyweights

So how is the definition of lightweights/heavyweight?
My weight is 88kg and I will sail it with 9.8 Racesail, so what shall I buy?
Thanks

Tom