Cobb is also a big name and pretty much the best in the Subaru world.
I have the AEM and who knows if it gives me more power. It doesn't lose any power.
The key thing is to go with a true CAI and not SRI. You need it isolated from the engine bay heat. Last weekend even the Porsche mechanic doing my tech inspection at the track noticed this and said "It's nice to see an intake done right with it in the fender well."