My 1.6A did 2.24 on a small, skived fin thermaltake 1U heatsink. Now it's doing 2.27 on water. It goes higher, but my room gets too warm after a while, so I leave it at 2.27 where I know it's stable up to a room temp of 95F.
Just try to maximize your potential. Get good thermal compound, like Arctic Silver Ceramique, and have proper case cooling. A good heatsink will do nothing if the heat isn't removed from the case.