Their air boxes make them special. The vacuum formed sealed air boxes are nice and it allows you a sealed system to attach a tube that runs under the bumper. They make/sell the ram air tubes as well. However, I don't think that box is worth another $100 over a K&N Gen 2 FIPK. With out the box it's the same thing as the K&N kit, so compare the cost.
Volant makes a great kit, and you will be happy with pretty much any of the top company intakes around. Have you looked into S&B at all? They have a great kit and I have never heard one thing bad about them. Everything from their packaging to instructions is top notch and they have great quality filters.
Yeah, I forgot S&B is in the kit business. I haven't seen one in person, but some of thier filters have an inverted cone on the end that is usually sealed up, adding even more surface area to the filter, plus the QC is a tad bit higher than K&N. K&N makes a plate for round filters like it, but I haven't come across another filter quite like the S&B.