Im not a big fan of cutting springs. I would try an 11.5 first from Cajun. The life of the spring will likely last longer, 11.5 will still set of primers reliably, and you can change them out with quick repeatability especially if you get a more S2s in the future. Also, I would just leave the factory sear springs. overall the gun springs will break in over a few thousand and you will enjoy it.