My friend is putting a system in his 2005 silverado extended cab. He's getting the Alpine 9855, jl 4 channel amp, diamond audio s600's for fronts and hasn't yet decided on the rears if any at all. And he's getting the jl 500/1 amp for his sub. Its gonna be a 12" in a custom sealed box under the rear seat. What kind of sub would be good for that? He wants good SQ. I've looked at the Adire Shiva's and it seems like too much power for that sub? But not enough power for the brahma (not really sure he wants to spend 380 bucks for a sub either). He was looking at the jl w3's and I'm trying to convince him otherwise. So any suggestions other than the Shiva? And is that too much power for the Shiva?