thinking about tweaking the sound system again..

right now i have..

Infinity 5 channel amp (4x50 and 1x300 at 2 ohms)

Boston Acoustics SX60 components w/ crossovers in the front

Rockford Fosgate shallow mount 6.5 2 ways in the rear

2 Rockford Fosgate 8" (stage 1) subwoofers in separate sealed (and very heavy) enclosure (they are 4 ohm rated at 150w each, i have them wired in parallel to make the effective resistance 2 ohms)

I'm starting to get tired of my sub box taking up so much cargo space... don't really want to go with a rear door mounted woofer.. so im thinking of going to a single 10" or 12" setup, but dont want to lose sound quality... right now my bass blends near perfect with everything else. any input on how 1 large sub would compare to two smaller subs as far as sound quality goes? Will i lose some overall volume/ sound pressure by moving to a 300w (at 2ohms) woofer from a pair of 150w 8" (at 4 ohms) getting the exact same feed