Highest flowing sbm heads?

i never much about the new Bloomer 200 cc heads with the 2.08 intake valve , i would think they would be right up there with any aftermarket stock type head . there is probably not much info on them since i don't think there are very many sets made yet . i heard rumors of 600 plus with a 250 @50 and 550 lift , don't know for sure if true .