There is a few variations of 300S as Hyosung is updating the look of the GV300S faster than we can keep up, there is now 300-SS , 300SA , 300R , i don’t think they will continue to make the early S model for much longer as they progressively move on from it.
2018-2021 (pre-facelift era) would be your safe bet for looks wise (plastics) if hyosung changes plastics, the frames would get updated with new mounting points which makes it harder to fit on to older models without modifications etc.
300S is more wide spread in asia that’s why and EU/UK is a larger 125 market, there are some german shops doing things like backrests, saddle mounts, even SHAD EU does nice hard tail boxes for them.
Exhausts = Look below:
Exhaust suggestion – GV125-S bobber Aquila 125 S EFi