This one could be fuel delivery. I don't run 99's in my 1150 dominator. Another thought, what is the alcohol content in German fuel?
FWIW My 1200 cfm Dommy has .082-.090's and has a nice linear fuel curve from about 11.9 at the hit and graduates to about 12.9-13.0 at 7000 rpm's and even Steve Brule at West tech dyoned two carbs of mine and was impressed with the curve. If you clean up the over emulsified carbs put out these days and size the high bleeds accordingly, you'd be surprised how little jet is needed............
