What is the benefit of a sports exhaust on a 4t scooter?

Hello, I'd like to install a sports exhaust (TECNIGAS NEXT-R CHINA GY6 4-stroke 139QMA/QMB) on my Rex RS 400 4-stroke (50cc). I was wondering if the top speed and acceleration would change significantly, or if it's even worth getting a sports exhaust. If I were to get one, what should I pay attention to when…

Is it bad to install a double layer air filter element the other way around?

Hello, I have a typical Chinese scooter with a GY6 engine, and when I open the air filter box, my current double-layer air filter faces out with the black side. Now I want to buy a Stage6 double-layer air filter insert, but if I were to install it (at least if it's delivered exactly as…