K&N is not bad for road cars. But I wouldn't spend an insane amount of money on an air filter and spend still more money on a cleaning kit for it. Simply no time to do that. I'd rather just slap on a new filter more often.

But there are instances when the freer-flowing characteristics of high performance air filters have been blamed for fouling up engine electronics (sensors). If the risk of fouling up your sensors is worth the performance gain, then by all means get a K&N.

I'm just Mr. Average Motorist, no need for that for me.

Open type filters also bypass the built-in anti-water ingestion features of most stock airboxes (the 4d56 air intake alone has a number of safeguards built in) which may be an issue of you ford water (or floods) with your vehicle.