I agree with all of the above comments. I know a couple people in the magazine business and they will do anything possible to sell ads. If a product had good reviews, that is a natural to get someone to advertise with them. If anyone reads Race Engine Technology, whenever there is an engine story, you can count on ads from the camshaft, piston, and valve train suppliers to follow. I have had to deal with air filters for HVAC a lot over the years and they are very similar to our filters. There is a trend to go with these "V" shaped patterns so that instead of a single flat surface, the material is done in V shaped ridges and essentially doubles the filtering space. If there is anyway to increase the filtered area it makes sense that it will allow more air flow. Yes, I would have preferred a test with a comparison of the stock filter, but I am guessing the manufacturers have (hopefully) done their homework and have tested their own product against the stock filter. In reality they have probably tested all of their competitor's products and have tried to improve on them. If not, why go to the expense of developing a product if you will get shot down in tests like this.