Not disputing what you have had done, but I`m struggling to see how it would physically work and connect? The term you are using of Bypass cable is confusing - what exactly do you think you are bypassing?
If you have the specific details of the lead / kit, then that would assist me (and others) as to how you have got around the problem. But tell me, does the sound come out of all four speakers, and does it also come out of the subs? If so, then I think I know what has been done, and the parrot has been "loaded" to drive the input side of the BOSE system (not 2 ohms, but a different range of voltages), and the term bypass lead is nothing more than jargon from the fitters.
:-/
I don't know the name or make of cable that was needed and I am not an audio expert thats why I suggested contacting Halfords Romford or the other company I suggested.
I have been told by several people that have this parrot kit fitted that they also needed a " by pass cable" if you have some sort of amp in the car. My brother in law had to get one when he fitted one in his range rover and was also advised he would need one on his BMW M3, both have a Harmmon Kardon system IIRC...
This is what Parrots website says for the Omega
"The installation of your hands free car kit needs a specific ISO adaptor.
Parrot does not sell this harness. Please contact one of our certified installers for more information."
Sorry I cant be of more help, just wanted to advise that it is possible to have such a kit fitted to an Omega because I have got one.
I will check where the sound comes from when my car comes back from the garage, it is away having cambelt and big service at the moment.