Is there a filter i can buy that will just fit on my stock car?(2002 gtp) Do i have to fab something up if i want a cone filter? Ive seen the k&n filters that go in the stock airbox. What do you guys recommend? I know i probably should go the pvc pipe route but I dont know if i want to if there is something easier. What kind of gains would this give me? Any better gas mileage?