First of all, let's dispel some myths about the restricting your moped or scooter. A 50cc moped or scooter in the UK is speed restricted to 30 miles an hour and has a restriction on the brake horsepower only when ridden by a rider under the age of 17 ( i.e. a 16-year-old)
While there are still some restrictions on what you can do with your bike in terms of emissions, noise and at the extreme level performance, for all practical purposes if you are 17 years or older and your insurance company is happy with the changes you make to your bike (and they probably will be) then go ahead and make the most of your 50cc scooter and get it de restricted and achieve greater performance.
Here's a simple video of that in action.
Of course, it does have some practical downsides. Firstly you will need some mechanical expertise to get the job done. It's nothing that you couldn't learn in an hour or two of studying this video and maybe getting out your bikes owners manual and seeing how to apply the knowledge you just learned.
Then of course you are running your 50cc scooter much higher in its performance envelope once you de restricted. This will mean the life expectancy of the engine and other key components may be reduced somewhat.
Given that most scooters mopeds of this engine capacity are normally scrapped long before their engine runs out this property is a minor consideration.
I would also suggest that you take some time out on private land or a safe area first to practice on your newly de-restricted machine. The performance will be quite different. For instance it may take your breaks a little longer to bring you to a stop. Be aware of all this before you set out in traffic!
Having said that, it's unlikely that your new 50cc de-restricted scooter would even come close to the performance of a 125cc machine anyway so if you're used to larger engines in the first place then that should be fine.