If you're talking about numeric raws, there are no numeric raw replies being triggered for those. /.server echoes right after you typed it: *** connecting to blah blah. /.hop says it's attempting to rejoin a channel, before it really tries to.
If by "raw" you mean mIRC internal work, well every command has its internal tasks being executed. It'd be quite possible to halt the default text for /server when even /.dns, which does use even an mIRC-run event, works quietly.