As for the speakers in the mach 460 I am not to sure. I too have heard both. As for a new set up I would reccomend that you get a custom box made to fit in the corner or corners (if you want two subs) of your trunk.
I have two corner boxes with tens in them. If you only did one corner I would suggest a 12 or 15 if you could fit it. Some good brands that are not over priced like JL and kicker, is MA Audio, Audiobahn, Digital Designs, and some
MTX. (mostly the top three)
I would go with one big mono amp and a capacitor for sure.
2008 v6 Pony Package.
Performance mods: Aluminum Driveshaft, Screamin' Deamon Ignition Coil, Red Livewires... and an STS turbo kit with an intercooler,and water methanol injection.
5 psi~ 286rwhp, 331 rwtq
Other Mods: Window Louvers, 2 10" MA subs, 1200 watt RMS Hifonics amp. Tial 50mm BOV.