well heres a long one for ya haha...

i goin for 2 s10l5's and 2 zx400.1 amps...kickers recommendation for one sub is 2.25 ft3,at 42HZ....i got a max of 3.33ft3 to work with and have no idea wat to tune the box to...im goin with 2 of these subs in the one box and am completely lost as to wat to tune to....any help greatly appreciated haha...listen to alot of rap hip-hop bit of techno and metal...lots of variety...heres the specs on the subs and amps.soon goin with sealed hahaha...box will replace center console..not tryin to copy anyone just the only way i can get enough space...2 subs downfire with port exiting to the rear....alsooo..gonna be probly another kicker 4 channel to run the speakers...would a better battery..maybe optima? and a couple caps suffice?

Kicker S10L5

Subwoofer Size 10"
Subwoofer Design Square
Voice Coil(s) Dual (2 voice coils)
Impedance (per voice coil) 4 ohms
Peak Power Handling 900 watts
RMS Power Handling 450 watts
Woofer Surround Santoprene Rubber
Woofer Composition N/A
Sealed Box Volume 0.66 - 1.0 cubic feet
Ported Box Volume 1.25 - 2.25 cubic feet
Sensitivity 86.5 dB
Frequency Response 24 - 100 Hz
Xmax (millimeters) N/A
Top Mount Depth 6-1/16"
Cutout Diameter N/A
Recommended Enclosure Type Ported / Vented
Sealed


kicker ZX400.1

Amplifier Class D
Number of Channels 1 - Mono
RMS Power (4 ohms) 200 watts x 1 channel
RMS Power (2 ohms) 400 watts x 1 channel
RMS Power (1 ohm) N/A
Bridged RMS Power N/A
Total RMS Power Output 400 watts
Peak Power Output N/A
Minimum Impedance Unbridged 2 ohms
Minimum Impedance Bridged N/A
THD at Rated RMS Power 1%
Speaker Level Inputs Yes
Preamp Outputs 1 pair
Built-in Crossover Low-pass (LP)
High-Pass Crossover Frequency N/A
Low-Pass Crossover Frequency 50 - 200 Hz
Subsonic Filter 0 - 25 Hz
Signal-to-Noise Ratio 95 dB
Channel Separation N/A
Bass Boost 0 - 18 dB
Bass/Gain Remote Yes
Fan Cooled No
Fuse Rating 40A x 1

Sounds like your on the right track.

why 2 mono amps? 1 bigger will came out cheaper and easier to install than 2 smaller ones.
I would lower the port frequency a little to like 37hz

the reason for 2 monos is cause i already have one lol i was just gnna get anoter the same