Collected these extra pieces today, it is only avaliable for customers who purchased the set 10213, from the shop, it is not avaliable to online buyers. These additional pieces are supposed to make the fuel tank more solid (they call the "stabilizer parts", well in simple terms just to make it stand better). 29 pieces to make the difference :)
Have to try and see the difference, i think this enhancement is from Lego Singapore only. For those who have this shuttle and would like to follow the instruction, i can forward it to you once i prepared a soft copy (but no lego pieces, :P)
Total 9 pages of instruction (2 pages actually showing the shuttle itself). More update when i complete the ship. Thanks to a friend, who informed me to collect these.