I would definitely +1 this, but add that after seeing a single 15" take the 5500 I would say definitely step up the power from the 3500 to the 5500 and these will slam. Hey Terric, really quick man, its not so wise to go telling everybody how much this person or that person can put to a certain subwoofer. At the end of the day, it actually cause more harm than good. Because the end user will listen to people on the forums, listen to what they see on youtube, and will try it themselves and many times end up having failed equipment, and which can come back to bite SSA or whomever in the ass. "Oh, well I seen this one guy put 5000 watts to a zcon, so I can too.". No, this is not what we want to spread. For many reasons, main one being, not everyone has the same experience, many people don't know what signs to look for, or how much is too much, etc. Then theres the whole thing about cost, and the electric systems needed for said system. Its just a whole bad of worm that IMHO should just be avoided all together. SSA is not "underrated", they have published power handling that a true and are not used as a selling gimic. They are provided for a reason and are givin for subwoofer longjevity, along with other reasons. Any subwoofer can be "underated", but is Completely install and experience dependent. They are many reasons beyond power handling means to go with a more powerful amplifier. Less stress, more unclipped power, which means happier subwoofer(s), cooler operating temps, etc... I would suggest yes, something like two 3500s would be a good match for 2 18"s zcons and placed in a wall as mentioned before. But be sure you have a stout electrical to back it up. Big 3, big power/ground cable, big alternator, decent battery bank, the works. After you calculate how much money it takes to operate such a system, you may want to take these things into considereation prior to making such a big decision. Good luck and keep us updated!