In my experience... a male that is never over fed will only get to about 1,000 grams full grown... The best breeders for me have always been between 750 and 1000 grams... biggest my males have ever gotten have been 1,000 or under... They get one properly sized rat per week. that is it. The proper size for an adult male is one small rat (or one med to large asf) per week.
Now of course I have taken in rescue males that were as big as females.... but that was from a long history of over feeding... They make for lazy, crappy breeders.