99% of the 49/H8 batteries will have a 90-92 AH rating...the specs within a battery class size is pretty similar among the major 3 battery manufactures (who make most of the battery brands in the USA).
The BMW branded battery is specifically designed to be a 105 AH battery...so that's one spec the dealer branded battery has over the others. If you don't have heavy electrical needs more than normal...a 49/H8 battery would probably be fine. I wouldn't go as low as a 48/H6 battery...as you can see in the chart above that it only rated as 70 AH. That's a lot lower than 105 AH of the original...where as the H8 comes in only a bit lower with 92 AH.
Why not just measure your battery compartment to see if it can take the 15½" length of the 95R battery...which is only approx 1½" longer than 49/H8. The height & width of the H8 & H9 are the same...its just the length that is different (battery case size wise).
