Tigerair of Singapore, in which Singapore Airlines has a stake of 32.8%, unveiled the first A320 aircraft to be retrofitted in Asia with Sharklets. Five A320s have already been delivered to Tigerair with Sharklet-ready wings, with the retrofit work being undertaken by Sepang Aircraft Engineering in Kuala Lumpur, Malaysia.
Sharklet-ready wings are already strengthened to the necessary levels to handle the bending and twisting forces introduced by the additional aerodynamic surface. The retrofit takes just 2 days for such ready wings. Non-sharklet ready wings will need at least 13 days of work with the sharklet-retrofit kit, which will be available only in 2015.
Jet Blue made “history" in the February of 2013 by being the first operator to perform a production retrofit, on its aircraft N821JB (MSN 5417 which first flew on the 1st of December, 2012). This aircraft was produced before MSN 5428, which is now registered as 9M-AQQ, flying for Air Asia, that had made “history" as the first Sharklet Equipped A320 to be delivered.
Factory fit and production retrofit can be better understood here.
In addition to its retrofitted aircraft, 9V-TRK (MSN 5697 delivered on the 26th of July 2013 to Tigerair), Tigerair will start taking delivery of production-fitted Sharklet aircraft later this year.
You can read more about Sharklets here.