HGG Community Forums

Technically, you can't boost horses in HJ2. In the first server, you can apply 5% boost tokens to horses, but the only instance of boosted horses I know of here were a run of Exceptional Darkest Night horses from a special Herd Helper. I think the last one from that HH died last year, but some clones survive.
You can change consistency, genes, and gender in the GMT lab, and you can change backgrounds in the tack page of any Warmblood horse. Light and Heavy breeds don't have a tack page right now because it has to be created first. :P