I have a 2008 VE AlloytecV6 Calais and I want to do some performance work.I'm thinking of doing a flash tune, under drive pulley system, OTR cold air intake and intake spacers."Are all of these possible to be done and what will be the cost of the same?

Yes they are: Flash Tune $550 http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/PPF601/SubProducts/PPF605 Under drive pulley kit $292 http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/PB620/SubProducts/PB621 Alloytec otr $585 http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/CAI624 12mm Manifold insulator $150 http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/MI603 25mm Manifold insulator $220 http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/MI631