70, no way a 904 is any safer. You dont see many because not too many mild 904s are being raced in comparison. If a racer has a 904, it's already been beefed up, and most know about the 2nd gear burnout. The geartrain and hydraulic systems are identical in 904s, and the material is the same for the clutch retainer. If the sprage gets rolled, the same issues arise.
