Depends on what you are doing .... tho I can't imagine the 6 (3 x 2 GB ? ) to 16 Gb (4 x 4 GB ?) swap.
look here .....http://www.tomshardware.com/reviews/ram-memory-upgrade,2778-8.html
Half Life gets a 30% performance gain, other games in that test, not so much. PhotoShop gets a 12% improvement from 6 to 16GB