[mr.fabulous]

I'd have said I would never buy a used car that was anything but bone stock, as I have no way to know the capabilities of (s)he who did any mods. It's not the parts, it's the installer. But, funny thing, I bought my car CPO last year and I really do wonder how factory it is (the windows have been tinted, very well I might add, and I later found a Garmin power supply and wiring for a radar detector... hardly "mods", but clearly a PO with some interest in these things). One never can know with certainty the history of a used car, and so you take your chances.