Me and my buddy have a little friendly competition going on between our systems. Currently i am running 2 12w3s in a nice ported box built to JL specs, powered by a fosgate 551s, in my single cab dodge ram. He is running a 10w7 in the JL h.o. box off a jl 500/1 in his 2 door tahoe. Right now its kind of a toss up between us, i may be louder if anything, but his sounds really good, and is just as loud. Is there a single sub i could use, powered by the 551s i have now, that can hang with that sub? I've wanted to switch to a single sub set up for a while now, so im ready to do this. I was thinking a 12 or 15 SE or maybe even a HC if i can get my hands on one, but is 550 rms enough to power a HC? I definately will be going ported, and the only issue is mounting depth cannot exceed 9 inches. Any other ideas are greatly appreciated, thanks for the help.