Re: 2 Sundown Audio Zv3 15's in the Scion TC.
Just as mentioned above, the Rquired box size for a given sub. Depending on the sub, the requirements for outputs differ, and all require different enclosures. I know some 15's and sme 18's that sound best in a very small sealed enclosures. Some subs sound best in ported, but your choice in subs will ultimately chose your enclosure types. On another note, there are no trolls in this thread, nothing but good information has been given so far. Which is awesome to see!!
Kenwood Xcelon Headunit
Boston Accoustics Front & Rear
Cadence United Series Vegas 4 Channel
Cadence United Series Dakota Mono Amp
Duralast 1,000 amp battery, X-Static 2,000 Amp Battery
Rockford Foagate 1/0 wire, and interconnects
Cadence shielded RCA wire
Dynamat sound deadening, Fatmat sound deadening