I thought the vains or what ever where of a slightly different design to help with the spooling up slightly, help get the V's up to speed. Again might just be something I've read but has no back bone to? Lol Just googled it, B has 9 blades A has 8 on exhuast and the compressor side B has tightly spaced blades, like 4 sets of 2 and A has widely spaced blades more like 8 individual blades. Not sure what effect this would have though? Lol