I have a pair of shivas, they are in a 5.4 net common enclosure with 41 sq in of port 30" long, this yields a tuning of about 26 Hz. The sound quality is very good. The bass is very very transient and deep. However, it tends to peak a lot at 40-50Hz. So, don't go thinking that just because it's ported you will lose sound quality. The peak makes the bass sound very phat and nice and powerful and deep. Just thought I'd give alittle imput.
DEQ-P9 (30band eq L/R, time alignment, 36dB/oct 4 way crossover)
Soundstream Tarantula (for subs)
Precision Power PCX-4125 (for horns and midbasses)
Image Dynamics CD2 comp mini horns
Scan-Speak 7" 18W/5535A midbasses
Subs still pending.