Sea Doo RXT 260 max rpm without titanium valves retainers upgrade

I read somewhere that with OEM retainers I can be safe till 8350 (stage 2) but here in another post I read that it’s safe till 8100, that is practically the stock limiter… so I must do the retainers with the stage 2? Why RIVA doesn’t put the retainers in the stage to but only in stages 3 and 4?