Enable the "Spawn Jetpack" code. When you have the Jetpack on, take it off. Then, get about thirty feet behind it so you have running distance. Run into it by using the running boost (hold Left Analog-stick Up and keep tapping A). Just before you run into the Jetpack, release A and keep the Left Analog-stick in running position. This will give you unlimited running boost until the Left Analog-stick is released.