The best thing to do when thinking of performance upgrades is to see the engine as a lung in the body. A lung inhales air & exhales poisonous gases.

 

Exhaust: Is the exhaling of the lung. Length, flow & width of the pipe all effect exhaling.

 

Air cleaner/Carb/manifold:  The inhaling of your lung.  A good quality filter stops the lung clogging up & becoming rotten.

The carb is the mouth opening size for flow. The manifold is the bronchi (separating pathways) of the lungs.

 

Jets/Re-mapping: The effectiveness of the inhale & delivery of the inhale.

 

Cams: Are the length & duration of each breath.

 

Heads:  The lungs capacity.

 The cheapest performance upgrade $ for $ is usually increase the engines size.(This is if you want more at a price).

Basically a motorcycle is a metallic human body in many senses: 

The oil is blood. Zinc & antioxidants are needed for longevity.

The oil filter is a kidney.

The skin is the paint & chrome.

The wheels are the feet.

The handlebars the arms.

The lights the eyes.

Fuel is food. The fuel's quality effects performance.

The longer you run the engine it the fitter it gets (with in reason).

Regular check ups spot minor problems before becoming major problems.

 

 

That's all there is to it.  You'll never look at your bike the same again.

 

Shadowhand.