Backing up what's already been said the 13B in the FD is often upgraded with 850cc and 1200cc injectors (can't remember which are primary and which are secondary). You can't really compare what they do with what a piston engine does. Hell people still argue what to compare (1.3L rotary vs. 1.3L piston or vs. 2.6L piston). Personally, I like the idea of going to HKS SS BOV's with the recirc option.
Another point on stock vs aftermarket BOV's. It's really a matter of boost pressure. The more pressure you run the better the sealing on your recirc/BOV needs to be. Also the larger the valve area you'll need when it opens to quickly drop the pressure in the charge pipes.
"The 300ZX Turbo is a dance; it's a song; it's rolling, roaring automotive art. There is no color that doesn't suit it. There is no mood-lifting chemical substance it can't replace." - Automobile Magazine
