For me, what I heard is:

Open Pod Filter provide more horse than Drop-In Filter but FC becomes higher than normal, Drop-in filter provide less horse power but better FC...

Is this true? Anyone plz correct me...

Open Pod Provide 13-14BHP....how about Drop-IN?

once you got open pod....you mod will be go on to get full potential of the open pod.

it's like PC, if your motherboard is cacat but you got super cun display card, the display card can't performed at full potential. So you must upgrade motherboard, then later need to add Ram then bla bla bla...the list goes on...