Scorpion on standard engine

Hi all,
I have just purchased a Scorpion exhaust for my new PX125 and I have some questions :

-Does someone know if this exhaust comes with the spacer needed to mount the spare weel?

-Since my engine is standard, no kit, do I need to change jet, carb, or sparkplug?

-a more general question regarding the air filter : is there any better way to duct air to the carb?