Need help with box 2 re sx18s willing to pay

[chance2727]

hey everyone this is my very first post! i am in need of a little helpand im willing to pay. previously i had 2 re sxx12s and a hifonics hfi2000d but it wasnt cuttin it for me. i have now bought 2 re sx18s dual 4 ohm and an re xtx5000.1 amp. now thats all fine and dandy however ive never had to build a this big of a box before and im not sure on what to do for a port. i would like subs up port back port in the middle with zero common walls. vehicle is a 2007 escalade my max room is 20''hx38''Lx48''w. they say 8 cubes per sub tuned to 34 hz.

subs specs are

18" (comes as SX18)

• Electrical Q Value -Qes: 0.53
  
• Mechanical Q Value -Qms: 6.1
  
• Total Speaker Q Value -Qts: 0.48
  
• Free Air Resonance -Fs: 33.2 Hz
  
• Equivalent Compliance -Vas: 159 liters
  
• One-Way, Linear Excursion -Xmax: 22 mm
  
• Efficiency -SPL 1W/1m: 92.7 dB SPL
  
• Effective Piston Area -Sd: 1210 cm^2
  
• DC Resistance -Re: 1.9 ohm
  
• Nominal Impedance -Znom: Dual 2 or 4 ohm
  
• Thermal Power Handling -Pe: 1000 W
  
• Force Factor -Bl: 21
  

any help is greatly appreciated! thanks in advance