You most likely wouldn't want anymore anyway. I do believe that is the limit. You could with higher quality horses struggle to find enough GI races for all of them to compete in. Some of your horses could suffer from the lack of enough starts each year. I usually keep mine down to 3 or less and I make sure that all of them are different in some way so that they do not compete for the same types of races. I might have 1 sprinter, 1 long distance and 1 dirt running at the same time.
JimCougar
CEO
ORLWorld