FWIW, the Cobra in our lobby is an M-plate car, probably a test mule for whatever group is developing that stereo system. I think it is a 2001 Cobra as it has the Mustang in the rear bumper, not the 99's with Cobra. Certainly not a 2003 Cobra. And it has the orange Visteon energy swirl sewn into the headrests.
I suppose it could sound very different than the production version in the 2002 GT's. I think the Mach 460 sounds pretty good for an OEM system, but the only difference I am aware of with the 1000 system is some functionality in the HU & two 10" subs in the trunk with their own amps. Not worth the asking price.
Oh, crap, we make those. So, I guess I should say they are the best investment in a Mustang so I can get a profit sharing check next year. Oh, well. I never said I was loyal.