Ah, this afternoon I went to Autobarn and bought a battery. The shop assistant was clueless, and at first offered me a battery (MF75D23L, 550 CCA) which would be too large for the compartment. Then he looked at the printed SuperCharge catalog, and said my car would have to be equipped with the battery MF40B20L (380 CCA). I told him the SuperCharge website recommended me a one step-up battery for Outback, MF55B24L (430 CCA). He told me the website was rubbish.
I checked the shelves, and they did not have the 430 CCA battery. So that I agreed to take the 380 CCA battery -- that seemed to be manufacturer's recommendation, anyway. They offered me a "special" price of $129 (the Batteries Direct website offers it for $120). I decided that I was tired to look for the best deal (in terms of both CCA and price), and agreed to get it.
The shop assistant told me their garage was not open today, so that they would not fit the battery. I thought that I wanted them to fit it, because if something went wrong in terms of size it would be their responsibility. I said I would buy the battery tomorrow... and they found a guy at once. When mounting the battery, he was not attentive, and short-circuited the battery with the spanner.
The new battery turned out to be 3 cm less in length. I am slightly bothered by the fact that the battery is slightly less CCA-capable and slightly more expensive than I could get, but I had already reasoned I'd be able to balance myself. The battery was manufactured this month which I consider as an advantage.
To Davidov: yes, I agree, the CCA does not matter because both 380 and 430 are above what is required to crank the shaft (~200 ?). However, in a few years' time, the larger current-capable battery would have a higher CCA, and thus would last longer.
