no they don´t. at least not in my book, the one of several mechanics and friends that have had one.
just the intake, w/o modifying the engine further leads to nothing and the reason is simple. the engine electronics in modern cars regulate fuel and air mixture automatically. even if you would have unrestricted airflow to the manifold, there would simply not get more air used than the system dictates. intake systems only make sense, when you change the electronics, with a chip for example and even than the parts have to be tuned together.
some folks say, that a direct intake delivers colder air = more oxygen. well, look at your bimmer and see where the original intake gets its air from...samething, different layout. there is also a filter...the pipe...if you want to add oxygen and power to the intake, get a turbo.
i don´t trust that stuff...there´s better ways to waste my money