Two different things. One is an in the fuel tank system and the BG is a through intake and the fuel rail system.
If you have a low mile GDI system the BG will do a better job but using the SI-1 would not be a bad thing to keep the injector internals clean.
If no GDi then a regular spray can throttle body cleaning and the SI-1 will do a decent job, no need for the more expensive service.
High mile GDI can have other issues that neither product will address, the injectors need to be pulled and cleaned professionally.