not got a pipercross viper but somethin very similar. its an apiro sealed filter with cold air feed, had it sittin behind the bumper when i first put it on and car felt bit better than normal induction kit. but recently i mounted it thru the front bumper so its now forced induction like its supposed to be. has made a big difference now and pulls a lot better. mine cost about £70 if i remember rightly. less than a normal k&n induction kit. mines a 1.8 zetec tho.