A lot of us have. AEM one, mainly. There*s a recent thread a few down from this one discussing it. $30 well spent, IMO, heck I think they may even sell them for $25 this week...
Any performance increase?? I just switched from the Mazda factory filter a Denso Air filter, but I feel the factory filter was better made & offered better performance. With the Denso I feel the acceleration is not as good.