Hi Dave, Elliott here. Did you see my reply above of fibre filling instead of foam? If not, you may want to read it as it might be helpful. Also, you shouldn’t need to add extra volume, also, pretty sure Nick doesn’t use any absorbers in his ported designs (as far as I’m aware) which is totally fair, it’s quite hard to predict how it will change the behaviour of the enclosure. So there’s clearly no problem with not using any absorption with this design, it just “may” improve things a little if you have some upper mid bleed from shallow crossover slopes.