I’m screwing around with radiators now. I have my little 8 inch in a radiator box using 2 10 inch radiators tuned to 28 HZ. A more traditional way of doing this is to use a single 12 inch radiator. This 8 Im using has a ton of xmax, but most 8s could get away with using a single 10 inch radiator. 4 8 inch subwoofers and 2 12 inch radiators would be a cool setup. Air space and weighting for radiator setups can be done a couple of different ways. A sealed box air space size with a really low tuned radiator (25 HZ or so), or a ported box air space size with radiators tuned at a more traditional 30-40 HZ box tuning. What I really like is being able to tune a small box to a super low tuning without the giant port or any port noise. I’m ordering dual 12 inch radiators for my single 15 to play with next.