That is very hard to tell, depends on teh ambient temperature and the quality of fuel/additives. Also you didn't mention if the internal components have been uprated to forged.
Even then it would be hard to say safely. The only way would be to monitor the knock sensor, and the ECU's ignition timing. If the ecu retards the timing too often, it would mean it is detecting more then expected pings. If the advancing-retard cycle seems normal, then it would mean that you are runnig a safe ignition baseline.
