Only if the engine is running rich to start with, will you see an increase in power on stock jetting with an airbox modified for more air flow.

If the chambers are clogged up then yes, you will see an increase in power when you clean them up.

My advice though, which will be echoed by everyone, is that if you're after more power then you MUST sort the carburation out at every stage of modification, or you're asking for a seized motor and a big rebuild bill.