Just don't smooth it as VW spent millions on development and found that those plastic cut outs help air flow as air flow doesn't just pile in it travels in swirls.
Bigger air feeds like cold air or R32 won't make a difference as the ecu knows how much air to draw in.
and those guides on drilling air box are silly like the one on vortex as someone drilled in the holes quite high up, which was fine with a deep standard air filter, but a new 'performance unrestrictive' panel filter was thin and therefor sat low and was below the drilled holes lol.