Bicyclists who want to gain speed without going into the speed controller box to remove the manufacturer's speed restrictions have several options.
Change your riding position. It may seem obvious to professional cyclists, but novices may not realize that riding in a crouched position will decrease wind resistance and increase speed.
Wear tight clothing, and zip them up. This will reduce wind resistance as well.
Ride on a full 48 Volt battery charge. Bikes run at their best when fully charged.
Install a higher voltage battery. There are some e-bikes that cannot handle this option, so it is wise to check your manual, but if your controller can accept a higher voltage battery, this is a pretty standard and effective fix.
Changing to street tires, if the bike is equipped with knobby tires. Resistance is also considered in this suggestion. Because slick street tires create less friction on the road than knobby tires, riders may be able to achieve slightly higher speeds.
Adjust the brakes on the bike. Friction is created by the brakes rubbing against the rim, but over time, breaks can slip slightly and cause rib rub, and even a slight rim rub can decrease speed.
Reduce the weight of the bike. Take into account things like reflectors, mirrors, and other accessories. Because speed is the goal, the bike should be equipped with the lightest weight option available.
Install a windshield. Many see this option as counterproductive since it will add weight to the bike, and it's certainly not the coolest-looking ride, but it does reduce wind resistance.