hey i am new here i have a 2005 sierra 5.3 z71 4+4 crew cab that i have done nothing to. i am thinking about adding a k&n filter to increase hp. what is the diff between a model 57 and model 63 in terms of which would benifit me more in performace gains. also any other brands would be considered it just seems like the k&n has the best performance gains. does anyone know if afe is any good cause their website says that the stage 2(AFE54-10092) has a 50 hp gain