Originally Posted by HIS4
I thought they were comparing to the base system in the 128/328 which uses 6" woofers and a less powerful amp (not that the hi-fi is all that powerful). But yes, the same system is available as an option on the 128/328.
HiFi systems (OEM amp) are the same in the 1- and the 3 Series, and use 8" woofers under the seats. Only the Stereo system (no OEM amp) uses 6" woofers, not available in the USA at all.
HiFi system (Logic7) is different, though.