There are tests out there that show more contamination of the oil when a "high flow" air filter is used. This makes sense as the filters tend to be less efficient at removing very fine particles from the air, which end up sneaking past the piston rings and get into the oil. However, most of these tests I've seen were done on large diesel engines, which pull a tremendous amount of air through the intake system, so the degree to which a passenger car is impacted by this is debatable. If you change your oil more frequently, this is likely moot.
The other issue with these filters and intakes is that it is unclear how much of the horsepower gain is due to reductions in flow restriction vs. alteration of the MAF signal. A small alteration of the MAF signal can cause the engine to run leaner, which will cause an increase in horsepower. Again, a 1 or 2% increase in engine output is not likely to cause any harm, but these filters and intakes are a favorite scapegoat of dealer service departments. If you install one and ever have check engine lights or other issues, you need to make sure you have a "mod friendly" dealer, or remove it prior to taking it in for service.
The other issue with these filters and intakes is that it is unclear how much of the horsepower gain is due to reductions in flow restriction vs. alteration of the MAF signal. A small alteration of the MAF signal can cause the engine to run leaner, which will cause an increase in horsepower. Again, a 1 or 2% increase in engine output is not likely to cause any harm, but these filters and intakes are a favorite scapegoat of dealer service departments. If you install one and ever have check engine lights or other issues, you need to make sure you have a "mod friendly" dealer, or remove it prior to taking it in for service.