Heatsinks work alot better when they are made from copper, and/or have copper heatpipes.
They have a special formulation of liquid in the pipes that when heated, rise, taking heat with them. When they reach the top, the heat is taken away, and the gas cools, turning it back into liquid. The process is repeated over and over.
This type of system is how water cooling works, and with heatpipes, the same type of performance (compared to a cheap water cooling system), can be achieved, and quieter than standard heatsinks too, since the fan doesn't have to work as hard, to get the same result.
So, I'd say to try with the stock first. If its not up to your tastes, switch