I bought this one 9 months ago for $130. Unfortunately it's currently listed for $174, but I'd say it's still worth it. Hugely improved starting for me. Old starter would crank for 2-3 seconds and with the upgrade it's less than a second. I'm actually shocked how quickly it fires up.
I have had this one on my wish list for some time. Havent ordered it, but it has good reviews from other RX8 owners. The advantageof the S2 starter is the cranking RPM, which most of the non-OEM ones also have.
Hijacking to post a starter that I can confirm fits an 04 MT RX8: https://www.amazon.com/dp/B07HM9L2RQ?ref=ppx_pop_mob_ap_share