Re: port size(sq inches) for rl-p 15.
ive had my RL-p15 in 3.15cu ft @ 28hz with 40sq. inches of port area (16x2.5), had no problems with port noise etc. the box was a coffin though since the tuning was so low
i say as long as you meet the recommended 30+sq. inches, you'll be fine
box builds for friends: Assassin 8, ARC 12D4, SWR-1241D, SWR-1541D, AW1206T, MTX 9512, MTX 7512