What you want to try and find is the reserve rating for the battery.
If this battery is the same one that is sold at autozone (just under a different label), then it is somewhere around 150. If you divide 150 by 2, and add 16 (a formula I found on e90post for converting reserve minutes to amp-hours), then you are left with 91Ah, which is closest to what your car is already coded to.
2008 BMW 335i Sedan | Sparkling Graphite | Sport | Premium | Navigation | Comfort Access | Logic7
Golf Tee | M3 Spoiler | LED Angel Eyes | 5000k Fogs | Resonator Delete | Black Kidney Grills | Black Finisher Rods | 35%/18% Tint |12mm/20mm (F/R) Spacers | Black Lines