Im building two subs with passive radiators and the closest ones I can find to the specs I need are the peerless 5.25". If I were to put two in each cabinet, the 48 g would exceed my ideal 45g. The effective port diameter that these radiators are emulating would be about 5.8". The emulated port length would be 165", about 6 inches short of my calculated ideal port length.This deviation is about equivalent to a 3% excess in port volume. Is this significant? Also I was wondering how I would calculate the voleme by the passive radiators in the box?