A fuse is simply a thin bit of wire (or other conductive material) that is designed to fail at a particular amperage in order to protect other elements in the circuit. The fuse doesn't regulate or provide amperage to the circuit. The base of the fuse tap pictured is protected based on whatever fuses you put in it (or it's stated max amperage).

However there is a problem with this device particularly if you use it with higher amperage as you have stated you intend to. Your radio and cigarette lighter will be protected by the fuses, but the wires feeding into the fuse block will be subject to a maximum of 50A instead of the designed 30A max. This means that if those wires are only capable of carrying 40A before overheating they could overheat and cause an electrical fire.

I am not familiar enough with the wiring leading into the fuseblock are typically sufficient and it likely varies from one car model to another.

A fuse is simply a thin bit of wire (or other conductive material) that is designed to fail at a particular amperage in order to protect other elements in the circuit. The fuse doesn't regulate or provide amperage to the circuit. The base of the fuse tap pictured is protected based on whatever fuses you put in it (or it's stated max amperage).

However there is a problem with this device particularly if you use it with higher amperage as you have stated you intend to. Your radio and cigarette lighter will be protected by the fuses, but the wires feeding into the fuse block will be subject to a maximum of 50A instead of the designed 30A max. This means that if those wires are only capable of carrying 40A before overheating they could overheat and cause an electrical fire.

I am not familiar enough with the wiring leading into the fuseblock to tell you if they are typically sufficient and it likely varies from one car model to another.