Re: 2.75" x 16.5" enough for a port??
the port area will work well. i recommend 45deg. off all of the port corners since you have a few of them. this will help the air flow a lot smoother. i assume your using 3/4" mdf. in that case, cut a 3/4" strip the height of your port and rip it down the center at a 45deg. angle. place these in the corners. shave down the opposite corners to match. the end port board can be rounded on both sides.
2006 Jeep Liberty
Adire Audio 15" Brahma running off Cadence A7hc, Clarion hu, MB Quart 6.5s and 5.25s running off old school Punch 800a4
146+db @ 38hz with 1200w and a single 15"
Lv = [(14630000 x R^2) / (Fb^2 x Vb)] - 1.463R
*Vb = vol. in cu"
**R = sq.rt. A / Pi (for square/slot port)