Q: Can I upgrade my AS2/ES52 audio system to AS3/ES53 by adding two speakers?
A: No, it is involves much more than two new speakers.
You need to do the following to get to factory spec AS3:
1. Remove old seven channel AS2 amplifier (made by Pioneer).
2. Remove seven old AS2 speakers (made by Pioneer).
3. Remove old AS2 cable harness.
4. Install new AS3 cable harness.
5. Install nine new AS3 speakers (made by Harman Kardon) and Harman Kardon logo on rear speaker grilles (4 door models).
6. Install new nine channel AS3 amplifier (made by Harman Kardon).
You need to do the following to get a working AS3 system:
1. Remove old seven channel AS2 amplifier (made by Pioneer).
2. Remove seven old AS2 speakers (made by Pioneer).
3. Add missing speaker cables to AS2 cable harness.
4. Install nine new AS3 speakers (made by Harman Kardon).
5. Install new nine channel AS3 amplifier (made by Harman Kardon).
Note that the AS2 speakers have different sizes, different impedances, and different frequency ranges than the AS3 speakers.
This upgrade is everything but cheap and easy...
My local Saab dealer did investigate the cost of this upgrade, i.e. rebuilding the AS2 audio system to what it would have been if the AS3 was a factory install. The cost, including all labour, came out at SEK 50 000, EUR 5 600, or USD 4 800. Lucky me ordered the factory installed AS3.
Swedish Saab dealers offer a "fake" AS3 upgrade, AS2+, consisting, at least in 1999, of a plain off-the-shelf Pioneer amplifier and a pair of plain off-the-shelf 6" x 9" full range speakers. I have listened to this upgrade and did not like it, especially not the full range sound from the rear.