48v 350w to 48v 1000w

I would like to upgrade my ebike to a more powerful motor, yet stay at 48v. My main complaint is that if I go up the slightest incline now, the bike slows down considerably...moderate headwind, the same...carrying 50 pounds of groceries the same. I am going to upgrade the controller...is there something else I have to change? The battery will upgraded to a 40 amp 48v life. And is the wiring of all 48v 1000w motors compatible with all controllers capable of handling that much electricity? I would like the controller to have regen, reverse, cruise control and an "overdrive" function (I think that is increasing the 48v to 60 or 72 to get more speed). What other functions usually come in a controller? GSM?

48v 1000w motor should have thicker wires so they can handle more amps and watts so it doesn’t melt the wires. You need to upgrade your controller say a 40amp the battery at higher then 40amps continues will be better for example 45amps or more.

Use 12awg or 10awg silicon wire everywhere you can with good high amp connectors. More amps will make your bike faster to get to top speed and more pulling power (torque) you will have. More watts higher top speed you will get.

With hub motors the thing that kills them is heat. If you want real power and speed to get up steep hills you will need good genuine cell 60v battery at least and higher amps controller but 40 amps will do for now and you still have to worry about heating issues, this is just something you need to keep an eye on.

Is your motor a direct drive or geared hub motor?

Thanks to both of you! It is a hub motor. I have not seen any available in China that are geared hub motors for this kind of scooter.