I have found that by reducing the sizing of the spacer between the two o-rings, the stock "bright red" o-rings work quite well. The stock spacer that comes with the shocks are 3.6mm. If you use the thick spacer from #6440 the spacer is 3.3mm and the black spacer from #6466 is 3.2mm.

This is definitely something to play around with to reduce the drag on the seals and to allow for more swell. I have been using the 3.3mm spacer, but will be testing the 3.2mm one in the future.