Will it be loud? Yeah, its four 15's...
Could it be louder? yeah if u planned it out a bit more.
You could probably get the same output with just 2 L7 15''s in the right box, compared to four sealed cvrs. I mean the four of them have a big cone area advantage, but sealing off 15's like that doesnt seem like the thing your wanting.
u want loud i take it tho.