Here’s the Difference Between a Regular and a Performance Air Filter

The clean filter was a marginal improvement over the dirty, the cheap was a marginal improvement over the clean OEM filter—though you’d run the risk that it’s because there’s maybe less material and thus less actual filtering—and finally the K&N performance filter actually showed the best improvement of almost eight horsepower over the dirty filter, and a 4.3 percent improvement over the cheap alternative filter.

Jason also ran a real world test measuring performance times from 20 to 60 mph, and then 45 to 60 mph for each filter. Interestingly, all of the results followed the same pattern of improvement from the dyno testing, with marginal gains all the way up to the performance filter, which offered the best, well, performance. It was 2.24 percent quicker from 20 to 60 mph than a clean, stock filter, and 3.24 percent quicker from 45 to 60 mph.

So who would have thought! The performance filter is actually a solid, if still marginal improvement over the stock sock protecting your engine. But it also appears to be nearly four times as expensive. I’m not sure eight horsepower is worth a 400 percent increase in price, but that’s up to you!