Not intending to be argumentative, but I've become jaded over the years with marketing claims from companies whose products sometimes actually reduce performance, or raise it in such a narrow band that they're essentially useless.
It's quite possible that some of the aftermarket air cleaners are an improvement. But since the engine is a system, to make proper use of them usually requires changes to intake & exhaust manifolds, mufflers & exhausts and ECU's. Even then, you might see a bit of an improvement at high rpm's, but a loss of low to mid-range grunt.
I think buying an aftermarket air cleaner is just fine. It certainly looks better. You might hear more of an intake sound that is pleasant. Even your butt-dyno might suggest an improvement. But since most of my driving is at 3,000-4,000 rpm -- I suspect that the factory air cleaner is adequate. If your driving keeps your tach at close to red line, then a full rework of the engine might reap rewards.
