Hi Brendan,
You have to use RAS to make the change and you have to clone the collection:
CrystalDecisions.ReportAppServer.ReportDefModel.ReportOptions iro = rptClientDoc.ReportOptions;
CrystalDecisions.ReportAppServer.ReportDefModel.ReportOptions myRPTOpts = iro.Clone();
myRPTOpts.EnableUseIndexForSpeed
Collection is not exposed so I'll ask DEV if we can expose them.
Don