The tomei breaks down to make fitting easier, I'm in the boat that it doesn't need changing till ya upsize ya turbo the pipe in between the afm and under pipe is more effective back to back between 2 V7 sti's mine and a mates he had bugger all gains by going with the full sillicone under pipe and me rolling with the hks intake kit with the standard plastic pipe.
He might have spooled a bit faster (not much) but we put it down to EBC's with his beingn ewer gfb g force 2 and mine being a hks evc4