Ok I started a thread a bit back on building for a Dayton RSS390HF15 ported. I have not begun that project yet as i am now contemplating going with a Dayton Titanic MKIII 15 in a ported enclosure. Real reason for the change in project is enclosure size. I thought i would be alright with the 9+ cubic foot ported for the HF but it is just to large for my liking. Can you guys help me out with a design spec. I was thinking 21 width, 24 height x 25 depth. I was looking at doing 2 ports 4" diameter placed on the front side along with the driver. I would like to have it tuned down to at least 18hz. The issue that i have is the port lengths do not allow for this as they are to long. Also will i run into an issue with air velocity. Suggestions on design specs and helpful ideas for tuning are greatly appreciated. Let me know your thoughts. Heck is this even the right sub for the job. I would like to go ported no larger than 6 cubic foot used solely for HT. I am planning on powering with a 1000w keiga. Unfortunately the wife bought the HF model for me as a Christmas present but i don't feel that i want to go that route anymore. Everyone gave me great input last go around so thanks in advance guys.