Sinnis Apache Constantly Losing Power “HELP”

Hi I have recently got a sinnis apache 125cc non efi model.
I recently replaced the exhaust with a performance exhaust and fitted a cone air filter. I also fitted another filter on the right angled tube coming up from the engine below the carb.

Since doing this the bike starts fine but has a slight ticking noise. Initial pull away is fine but as soon as I pull the throttle back it greatly losses it’s power.
What am I missing? Would a EGR blanking kit fix this?

Thanks