A Subaru runs a under tray for protection but everyone I know gets rid of it strait away and doesn't worry about protection from the elements really as I don't know of anyone that has had problem arise from not having one , and the scoop tends to let a lot of stuff into the engine bay anyway so from a Scoob owners point of view we don't bother ,,, the VW ej20 does have a bit more room around it to let stuff in but with keeping the crap out you might also be holding unwanted heat in
Just my thoughts really as the VW side of things is all still new to me
