Depends largely on the quality and thickness of the bottles.
Look for a carbonation calculator on-line to get a feel for what measure of dextrose equals what volume on CO2. Safest bet is that the Belgian bottles will handle at least 3 volumes and some up to 5. Note that many of the really highly carbonated beers tend to go into really thick bombers or 750mL bottles and get corked and caged.
I'd not suggest any more than 3 vols in a standard brown bottle.Even that is pushing it for many of these cheap, thin, bottles.