you're asking about the partition in the middle? if so, it won't affect the performance overall, as the volume is still the same for each driver. The advantage of dividing a box is; extra stiffness, as the divider is usually an internal brace, and in case one sub fails, the other side still operates properly(the volume does not immediately double for the sub that is still working). The seems you have to worry about are the edges since you don't want a leaky box.

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2004 300M SPECIAL
Alpine CDA 9833
Alpine Pxa-h701
Alpine Rux-c701
Rockford fosgate p400-4
Rockford fosgate p4004
Hifonics BX 1205D
JBL c608 GTi
JBL p963
Infinity 2.5" center channel
Alpine type R 12"(2)
200 amp alternator
yellow top battery
0 awg power and ground (welding cable) 300 amp anl fuse
all active SQL set up with 2000 watts rms