Hey Mate, I've got a Tecnigas Next R pipe on mine from the UK aswell.
I also bought some 8gram Dr Pulley Slider Weights for £17 which are great.
I have an unlimited CDI also, but makes it rev to 12000 which I dont want.
Seemingly Italjet Forumla Exhausts will work with the bike, but may struggle to fit the R50x for the rear disk brake. My mechanic got new brackets for my Tecnigas and it fitted perfectly, added 12mph onto top speed and acceleration was greatly improved.
I was looking for a 70cc kit but couldnt find one in the uk for everyday use.
Came across a 65cc Kit however for £65 on eBay from a UK Seller for the R50X.
Let me know if you want the details.