with lower power it would be better (l5) its more efficent than the l7 in that reguard. think of it this way. its a smaller v-8 and can run better on cheaper gas (87 octain) than an l7. in terms of sq solobarics arent a small box sub at all. their boxxes require propper bracing and propper deadening and the seal around the woofer must not leak,
i doubt youd notice much of a difference in SQ between L5s and L7s.. ive heard them both plenty of times and neither really sticks out as having better SQ. L5s are pretty loud though and when compared with the L7 definately hold their own. only big difference is power handling