I don't know what they mean about the snorkel being restrictive. It has a larger diameter than the intake itself. Also, theoretically, at highway speeds, it drives in more air, but I can't say that it makes a difference. The stock box and all the crap that goes with it is quite restrictive. I did notice a gain in power with the Volant installed, but I cannot prove that and I seemed to get better gas mileage. However, since putting on 33's any gain was sucked up by the bigger tires. I am very happy with the Volant and the snorkel combination.