Hi guys, i spent alot of time searching and reading on the several threads there are regarding this issue on the forum and just thought i would share with you my experiences from yesterday and hopefully sum everything up in one thread for people searching in the future.
I purchased a full bose set up (4xspeakers, subwoofer and amplifier) around 2years ago before realising though reading on here that it was a mistake as they wouldnt fit without rewiring the whole car/wasnt worth doing for the small benefit you would get over the standard system so for 2years it has sat in my garage doing nothing!
I had the job of replacing my drivers side arm rest yesterday as it had worn and whilst the door card was off thought it would be silly not to at least try to change the speakers. I found that the front speakers were a direct swap no problem at all (2minute job) so thought i would attempt the rears. These were slightly more difficult as the connector blocks were different, however an easy solution was to snip the connector block off and use a scotch lock to connect the wires from the speaker to the wires in the car (5minute job). When it came to the sub, i didnt even attempt it once i saw the difference in the amount of wires and the difference in connector blocks between the bose sub and the wire in the car. I also understand that the standard subwoofer has a very small amplifier inside it which powers the sub and rear speakers, whereas the bose sub uses a separate 4 channel amplifier, which didnt look easy to fit either.
So to conclude, the two front and two rear speakers can be changed and replaced for bose very easily, however the subwoofer/amp is a much more difficult task and more effort that its worth probably! Which suits me well as i plan to purchase an AndyMac sub enclosure at some point anyway which will be far superior to what the plastic bose enclosure could have produced!
I am lead to believe that i will not be getting the full performance from the bose system (the rears in particular) as they are being powered off the small amp inside the sub as opposed to the separate bose amplifier, that said in my opinion there is a noticeable difference in sound quality and loudness over the standard system. Its not an ear piercing bass shattering system, but you will never achieve this whilst running any speakers/sub through the tooth floss thin speaker wiring they fit in our cars as standard! An aftermarket set up with a complete rewire of the car (which i hope to afford and upgrade to at some point) will always be alot better but for a cheap and easy upgrade im very pleased with the bose!