The Vipec has inbuilt knock detection. The earlier Link G4 Extreme had them AFAIK, and when Vipec negotiated , part of the deal was the G4 couldnt have knock control, and something else that i cant quite remember right now. Im sure someone with the exact differences will jump on soon. Lithium will probly know.
The link, you need a knockblock. It can be permanently wired into an input, or just use it when your tuning, like i did.