So i have gone ahead and started my calculations......... I am hoping that these are right. The piece of pipe is 55"x24" so my volume in cubic inches is 2,073.456 and the fb/cc opening is 8.29 and is the area under the rf plate and area at the end of the rf plate and the minimum volume of the fb is 684.24 so my fb should be close to 24x24x18? For the area under neath the rf plate is that measured from the bottom up the side wall of the pipe? Also what should my thickness of my end caps be to close off both ends of the pipe? The pipe is 3/8" thick should i follow suit and buy 3/8" plate? I would appreciate any help at all to try and get me through my first build I am excited and cannot wait to start!!! Thanks in advance