Does a Carb neeb to be retuned after
1. Air Filter Upgrade
2 Spark plug / Plug Cables upgrade
3. Pumping Fuel With aditives? (eg: Vpower)

Read around If u dont retune the carb, there will not be any diffrence. 

On another case,
I tried filling my car with V-power the last 3-4 fills.
I noticed, The Engine knocks More, and I get Very bad mileage (like 40km less). As a lot of people used it and they said its very good and gives em extra mileage..
Im wondering if The engine needs to be re-tuned to accomodate the fuel?

Now im back to normal Esso/mobil.. Engine Knock is not that much. 

Nono..just a curious question.
Cause after putting in V-power (which everyone claimed it gived better mileage) My FC went up considerably high..

So i was thinking maybe the carb needs to be re-tuned to accept Fuels with additives like these?

yes they do.but i scared they will say 'itu biasalah,proton' as someone already faced before.or maybe i scare too much