Here we go again...the stock cooler is actually good enough. If you're going to upgrade, your looking for something quieter, but you're not going to get a lot more boost performance just out of a new cooler.
I certainly wouldn't spend $65 on a 4 heatpipe 120mm setup. You might as well get a Coolermaster Hyper 212 for less than half the cost. I can't find a review for the "S" but the larger "L" wasn't a great thermal performer.