That's for the JB2. I think he meant the JB3 2.0, which includes a "race gas" map designed for 100 octane. Gains are pretty impressive...the JuiceBox 2 is entry level few wire piggy back unit and increases boost about 2-3 psi and is safe for 91 octane. Sure you can use 103 unleaded octane. Its a waste of money and you wont feel any difference since the spark map is tuned for 91 octane.
Stick to unleaded though, leaded will destroy your cats.