go.
been pleased with my nitron street series 2 thus far. they do give you dampening adjustment over the quantum zeros. not sure if that matters to you, but it might come in handy on the occasional track day. also very easy to adjust.
I'm about to pick up a set of the NA Penske's as well. We might have a group buy.
Think I answered my own question: the black ones are the series 1 and the blue ones are the series 2...