... than use any 18's in any space on any amp with anything else, do whatever you want.
You're so vague in all of your posts that we can't help you, it's irritating that not only do you not give us specifics, you don't even know what questions to ask. If you were ready for 2 18's than you'd be able to answer your own questions.
I'm finding it hard to believe you'll do 2 18's, or even own a vehicle.
2 18s in a car is going to mean a wall in the back seat. I figure since you said you listen to hip hop and want to bump go for some 12s. But your best off just going to a higher end car audio shop because with the info you gave. It will be a project you couldn't handle on your own
You won't have the room for a proper enclosure for 18s. Do a couple twelves or a single 15, ported low in as large of an enclosure you have room for. Should satisfy you.
Making noise is one thing. We can all do that by touching some wires to some other things. There is much more to think about here, in order to get the most bass with ur space. 2 18s will not fit. Its that simple. They technically could but u would b choking them ssoooo bad that 10s with a proper install could beat them 18s up. Go 2 12s or 115 U mite could even do 1 18........ but remember.. ur box = 75 % of the bass u make. Pairing the right sub to the right box = 10%. Amp, power supply, HU, and myriad other factors beyond ur comprehension = the final 15%. Be specific with ur ?s annd we will guide u grsshoppa
I suppose you didn't take into consideration the dynamic pressure you'll exert on the polar axis of the motor structure? Sub-dividing the linear phase will be a MUST. If the ohms of the output signal aren't balanced with the crossover ratio then you'll be in big trouble. The Jackhammer was designed and intended for extreme bass with possible pressure recordings in upwards of 185 DBs!!!
Throw in an oscillation transverse multiplier and you could add 5 DBs to that number. Buddy of mine has one and he blew out the windshield of his neighbor's car! There are rumors that even basketball backboards have been victimized by this insane beast.