The non-Bose speakers are some OEM junk, I don't think there are any manufacturer's names on them.
The HU in newer 3's is made by Clarion; I know they switched manufacturers at some point (probably starting with the 06's); I don't remember who made the HU's for the 04's and 05's.
Your "can I hook up a sub" questions are easily answered by doing a search, but in a nutshell:
1. There are no line-outs on the factory HU.
2. To hook up a sub, you need either a line-out converter (LOC), or an amp that accepts speaker-level inputs. In either case, you'd be tapping into the speaker outs coming from the headunit.
The HU in newer 3's is made by Clarion; I know they switched manufacturers at some point (probably starting with the 06's); I don't remember who made the HU's for the 04's and 05's.
Your "can I hook up a sub" questions are easily answered by doing a search, but in a nutshell:
1. There are no line-outs on the factory HU.
2. To hook up a sub, you need either a line-out converter (LOC), or an amp that accepts speaker-level inputs. In either case, you'd be tapping into the speaker outs coming from the headunit.
