Malibu did not, and still does not, offer a factory Plug-and-Play solution for the bow of the boat (although they do offer an optional 350lb bow tank). Because of that, you have two options for adding bow ballast to this boat:
1. Use a portable pump solution to fill and drain bags under the bow seats. This is nice because it requires nothing to install, just open the box and head to the water.
2. Install an automated system to fill and drain the bow ballast. This will give you the convenience of push-button control, just like the factory bow tank option, but is much more involved from an installation standpoint. We can supply you with all of the components to tackle this if that's the direction you want to go.
Consider those options, and contact a ballast expert for specific product recommendations once you know which direction you want to go.