performer RPM air gap v.s ported LD4B

some folks on this thread are indicating that there's "no appreciable difference" in performance from the ld340 to the rpm air gap. i made this swap on my 340 (10.5 comp., mp .557 cam, 750 holley), and i can tell you the air gap made a HUGE difference.
get it, you won't be disappointed.
my 2 bits