this Is what I got from Bassbox. 

Driver Properties
  Name: ICON 15 D2
  Type: Standard one-way driver
  Company: Sound Solutions Audio Inc.
  Comment: ICON series
  No. of Drivers = 1
  Dual voice coils = parallel
  Fs =  26.8 Hz
  Qms =  6.6
  Vas =  4.241 cu.ft
  Xmax =  0.827 in
  Sd =  125.6 sq.in
  Qes =  0.49
  Z =  1 ohm
  Pe =  1250 watts
-----------------------------------------
Box Properties
  Name: 
  Type: Vented Box
  Shape: Prism, slanted front
  Vb =  5.418 cu.ft
  Fb =  22.7 Hz
  QL =  5.612
  F3 =  24.57 Hz
  Fill = none
  No. of Vents = 1
    Vent shape = rectangle
    Vent ends = two flush
    Hv =  14.25 in
    Wv =  3.5 in
    Lv =  45.57 in

Maybe you can try a bandpass enclosure ported through that opening. Normally wouldnt suggest a bandpass but mite help out with your situation

Lol!  that was my original plan with 2 10" soundqubed hdc3.110. Kind of a band pass blow through. I kind of got talked out of it on another forum. Also got pointed away from the soundqubed and to the ssa icon. I got away from 2 10"s to one 15". Funny it is almost full circle again. That being said I am not going to rule it out. Won't it require more space though?

 

Edited September 1, 20178 yr by ScotnEmily

Actually I was going to do 2 8" subs in the beginning, but was afraid I would not get the bass I waned, so I changed it to 2 10" subs. I have a few different blow through box ideas, but the one above is the one I was leaning towards the most. another had the subs facing  the same but the port came out between them. another they were facing each other. You get the Idea.

Get 2 10s or 12s Xcon and have fun ! Sealed or ported, you'll love them.

 

Icon or Xcon ? I've tried both, and loved both...but get the Xcon(s) for that 740.

Thanks I will definitely consider your advice. 

Do the calculations I posted above from bassbox look ok? Do I need to change box size, or port tuning on it any?