0.05 mm thicker, 5 hundredths of a mm. Which I don't think would make ant real difference (unless, like Dave mentioned you are casting to the horizon) Most of these sort of rules are to prevent anyone going in silly with 8lb or 10lb bs imo...... If they are sensible, then your original line would be ok in the 16lb........ My last club had a similar rule, impossible to police, especially when you take floater and zig fishing into account... I'd just stick with your old line, 16lb is plenty strong enough......