the bmc filter is enclosed in the carbon housing to stop heat soak. They have one end as a cold air intake and the other end goes to your tb.
The pipercross one is just a normal induction kit that without a proper cold air itnake and a proper heatshield it will jsut suck in loads of hot air.
Ive just recieved though the post my pipercross panel filter and ive already drilled the airbox, so should make a nice difference.