I agree with stuffing the ports too. You may want to position them differently (more or less toe-in - closer or farther from front or side walls - etc).
If what you are asking about adding 'fill' as in adding sand or shot to them that will tighten the sound from top to bottom. Try one thing at a time. Adding 'fill' may also make them forward sounding .
That's my opinion and good luck
If what you are asking about adding 'fill' as in adding sand or shot to them that will tighten the sound from top to bottom. Try one thing at a time. Adding 'fill' may also make them forward sounding .
That's my opinion and good luck