Hi Emanuel!
It is important to know if you have a two stroke or four stroke engine. All the mods depend on that.
The easiest way to recognize what type of engine you have - two stroke engines need two stroke oil, they burn it together with gas. There's an oil tank which you have to fill regularly.
On contrary, four stroke engines don't burn the oil (at least shouldn't do so in large volumes) but you need to change the oil from time to time (for example once in a year).
Here's some info from another thread (about CVT) where Chaz and me discussed our current upgrades.
Chaz wrote:
CVT mods as follows: Malossi variator kit 519988 with Malossi 9gr rollers that came with kit, OEM torque spring because Malossi White torque spring that came with kit is way too stiff, and Malossi yellow plastic torque controller 2512828 extra part not included in variator kit. I believe everything else is OEM. This set-up works really well with my other mods: Tecnigas Next-R pipe, re-jetted carb 108 main jet, 45 slow jet, and pod air filter (and derestricted CDI).
My setup is currently OEM variator, OEM torque spring, Malossi 7 gram rollers, Malossi torque controller 2512828. The bike runs great with Tecnigas pipe, OEM filter and derestricted CDI, regarding the jets I still have to check them as I don't know the size. Bike has smooth acceleration, has power to climb hills and the RPM's are always nice. The top end speed regarding to the Kymco speedometer also is upgraded thanks to the CVT upgrade by around 6 kmh (I have top end around 80 km/h now), although I haven't confirmed this with a GPS device.
So all in all, Chaz has a bit more advanced mods and probably his bike is running faster, but I'm very happy with mine the way it runs currently, and as you can see I didn't need many aftermarket parts to achieve that (rollers, torque controller, tecnigas pipe, derestricting the CDI/variator. Probably the jets were modded too).
I would advise buying the Tecnigas pipe and getting rid of the speed limiters (derestricting the bike). You will have to cut / replace the CDI, remove the washer from variator drive boss (if you or previous owner haven't done that already) and probably change the jets and set up the carburetor properly because the Tecnigas pipe itself probably will change the way your engine responds to throttle. Then you can start with transmission mods (CVT, also called variator) which doesn't change a thing in the engine, only in transmission - but big improvements can be achieved by doing them (after the upgrade I can ride at over 60kmh on very steep hills, while before the upgrade of the CVT I barely managed to hit 40kmh on the speedometer). I know it sounds like a lot of work, but that's not true. It's quite easy and there's a lot of information here on the forum. Plus, you can always make another thread and I will do my best to provide you with answers.
Check out which Kymco People 50 model specifically you have (year/engine/version).