Yeah, wor Shad a very bad experience with his.
I had a malossi on my agility but I didn't really get a higher top speed out of it. Maybe 2-3 mph.
Bigger difference maker will b new variator, high quality sliders and try the gates belt. On a 50cc you'll only make small gains. No major changes will occur by changing a part.
I put on a big bore kit and I only increased my top speed by 5 mph really...
My next upgrade? 150cc super 8!