: I was going to get the K&N filter kit from BAS. I read something on this board about it sucking in hot air and doing nothing at best for your engine. Is this the case? If this K&N kit is not worth it, what is? What can I replace the factory air filter box with that will actually increase performance? It seems that BMPD sells the same kits, except that they offer a heat shield on one. Is the heat shield the key? Any help is greatly appreciated.