Re: a55 stock airbox coupled with v-stack
Yes, if you're not facing the trumpet into the wind with no regard for what all the dirt will do to your engine, it's good to have a space to "set up" the airflow into something more laminar as it approaches the carburettor. With the snorkel cut properly the Tomos airbox can do an okay job of this for a 50cc motor - and it should should do an excellent job with the trumpet in there as the OP has done - but the box needs to be larger for a kitted bike.
For the complicated math behind designing an airbox as a silencer, see the wiki. But, if all you're worried about is performance, you need only worry about the simple math in the first section, that is the volume of your airbox must be greater than 10 x your displacement and less than 20 x your displacement.
I like how Tomos has the air inlet pointing into the frame, it kind of makes the frame act as a crude scoop. But, I have no idea how effective that is.