It doesn't. Otherwise, it would still be in operation when the off-road maps are loaded up. The TOR map has it open at 900 rpm (essentially at idle), and I'm not sure what the Arrow map does. Most people I know who are trying to get an extra horsepower or two out of a 675 motor just remove the whole vacuum system and call it a day.
It's a squid thing. You wouldn't understand.
Go soothingly on the grease mud, as there lurks the skid demon.