Indicated max RPM on the tach, and dyno sheet, was approx 5400rpm. That's within factory specs (on the high side, but still within spec). The Crazy Finns have pushed these engines past 5500 without pump failures, so I don't think it was necessarily the RPM at fault. But if my pump was on the way out (hairline fracture in the casting?), the high RPM likely hastened its demise.