It's not so much a question of what BPS the board is capped at; it's more a question of how fast the gun will cycle. Stock, these guns can manage 12 or so. With enough work, they can be made to cycle in the low 20's. Granted, you have to replace the board or add a $20 Tlaloc chip along the way, but there are a significant amount of other mods that must also be performed before asking the gun to cycle faster.
Modding a Rainmaker is a fun and rewarding experience. There's nothing like the feeling you get when taking your completed pile of parts to the field and seeing how good it shoots.
