Almost any airbox modifications will require rejetting due to the increased air flow. The routing of the snorkel for the stock machines is to get the air intake up out of the dust. Probably the most important thing you can do for your buggy is to keep the air filter clean. In stock for the airbox setup provides plenty of clean air. For a modified engine there are options available to increase airflow to the engine. Look at some of these pictures.
http://g2buggy.g2-innovations.com/images/other250s/other250s.htmIn most cases the snorkel is removed, and a custom airbox and filer that CAN deliver more air to the engine is used.
Unless your engine is modified with porting, a larger carb, and a performance pipe, the stock airbox setup is fine.