Interesting, I have a 2012 RSS. Maybe Ron will chime back in.
As with everything, the bars and links are a work in progress. I'll quit changing them when they are perfect!
If someone needs more information just PM or email me.
Originally my Billet Aluminum Heim Joint links were offered only as an option which could be purchased separately. Some even purchased these links to install with a stock sway bar, especially for the problematic 2013's.
As the Spyder models have gotten bigger and heavier, I've made sway bars to fit the need. The 2013/14 RT sway bars are the strongest, and therefore put the greatest amount of stress on the OEM plastic links.
I did testing on several of the OEM plastic links and none failed. But this was short term, not long term testing.
Though most OEM links have held up well in actual service, some have not. My feeling is that there is a variance in strength in the OEM links. But regardless of the reason, to me link failure is unacceptable. Some have failed due to road debris impact, some due to wear or fatigue, and a very few have simply broken for the assumed reason that the stress applied exceeded that particular link's capability.
I am still evaluating, but at this point I will not sell a 2013/14 RT sway bar kit without my stronger links. I may, in the near future, expand this requirement to more models.
I do not like to require customers to purchase something that is not needed. But safety and reliability are very important to me and to my customers. Right now it is rare for a customer to purchase a bar from me without the link set. And I do recommend getting the links with the bar, especially for the 2010-2012 RT's.
The 2008-2012 RS/GS/RSS bar exerts the least amount of stress on the links. With the narrower wheel base and lighter weight, this bar does not need to be nearly as stiff as the other kits. But you have to remember, you're still dealing with plastic which can stress and fail over time regardless of the Spyder you ride.
Again, to be fair, the OEM links have held up in the majority of cases. But plastic is plastic.
The OEM links seem to last quite some time (though some have found the ball to be very loose when replacing them). That is because these are a wear item and will need to be replaced at some point. My link sets (as with the sway bars) come with a lifetime replacement warranty.
Hope this helps.