If you haven't found already, I've used AllData diy for my FSM needs, as their subscription is cheaper than Subaru's. The official FSM on Subaru's STIS (Subaru Technical Information System) is severely expensive and generally not worth the price for private individuals to use.
AllData, though not always complete, generally has a good chunk of info that should be plenty for many DIY'ers. But like the official FSM, it's often not complete.
"Why would I want to profess my feelings for some 3D girl?" - Tomoya Aki from the anime Saekano