so i wanna get a couple alpine 12's in the cobra with the mach 460 with a 800 watt amp and alpine dvd touchscreen head unit. but they dude at best buy told me that my car has like some internal amp wired to the system that runs a different kind of wires or something so to put subs and an amp in they would have to charge me 1000 bucks to rewire the whole system. does this guy know whats goin on or should i go to like a custom shop instead of best buy.