Spark Plug Related: BR9ES or BR10ES?

[Snek]

Hi everyone. I have a 50cc (2 stroke) that has been fully de-restricted (Apart from rev limiter in CDI). It has an after-market exhaust system, snorkel removed from airbox, carburettor plate removed (limits air flow), de-restricted manifold rubber, performance race reeds, sprockets changed, and then re-jetted.

After researching online, I found that many people swap plugs to a cooler one after the de-restriction process. I believe the higher the plug number, the cooler the plug right? So I was just wondering, would I need to change my plug from the original BR9ES to a BR10ES or not? Thank You.