It won't hurt to have a broader knowledge of turbine systems and general 121 operating philosophy. You won't need to know how long the escape hatch safety rope is or at what frequency the ice detector vibrates.

Systems training was pretty lacking and consisted almost entirely of CBTs that you'll do during a week off from in-class training after basic indoc. You will be tested on it, but it isn't very difficult. Understanding at the rote level.

Where you will need to concentrate is reading manuals (FOM and SOPM) and applying them. Listen during lectures and study when you get back to the hotel. There really isn't much downtime and after the ground validation the pace picks up. You'll be learning something new every day and you'll be expected to stack it on top of what you learned the day before. If you've never flown a jet or worked in a crew environment you can be left wondering why you're doing what you're doing and mixing up steps. Maybe it helps to think of the why, maybe not. Depends on you.

Our class had a 93% pass rate. Most of them CFIs with no turbine experience. Some with 121 experience, some with type experience.

Just make friends with your classmates and study with them. They are your greatest asset.

Good luck! Feel free to PM me with questions. I'd be happy to help.