Out of the stock heatsink and fan combo, the heatsink would quite a bit more to replace than the fan. Plus, as an added bonus, most enthusiasts usually have spare fans lying around. What I'm going to do is replace the low profile 80mm fan with a standard 80mm case fan. An average case fan would provide higher airflow and pressure than the stock fan. Sizing wise, the design of the heatsink is designed for use with an 80mm fan. Perfect.
To remove the stock fan from the heatsink, first remove the shroud, then the heatsink from the video card. The fan is affixed with 3 Phillips screws.
Since the original fan is being replaced with a thicker fan, the original shroud cannot be used without cutting a bigger hole for the fan.
I don't want to permanantly modify the hardware, so I made a cardboard shroud. To do this, I traced an outline of the original shroud on a piece of cardboard and cut it out. For the fan, I cut out an 80mm square for it.
After everything was cut out perfectly, I taped down the shroud to the heatsink and zip-tied the fan (blowing inward)to the video card.
Two different 80mm fans were tested with this configuration, rated at 34CFM and 45CFM respectively. The 34CFM fan is quiet and from my subjective evaluation, cannot be heard over my quiet case's noise. The 45CFM fan was a bit louder, but not even close to the loudness of the stock fan running at 100%.