I have a crankcase evacuation system on my E16. They are commonly used on racecar engines, and that's where I got the idea. I'm pretty sure you can get a kit to install your own from Summit or Jegs. I pieced mine together myself. They are reputed to save some HP by decreasing the amount of windage [slung oil] from creating a parasitic drag on the crank counterweights. Basically, it consists of a 3/4" diameter threaded steel pipe fitting that gets welded into the header collector at a 45 deg. angle. Onto that threads a one way check valve, [I used a junkyard air pump check valve from an old Buick V8]. From the check valve, you'll slip on a length of 5/8th's heater hose that leads up to the [larger of the two] breather fittings on the valve cover. Plug the other fitting, so you seal the crankcase. The system works like this: when the engine is running, the exhaust gasses flowing through the header collector pass this 3/4" orifice [in the welded fittingin the header collector], and a vacuum is created. You are using this vacuum to "suck" the crankcase vapors out of your crankcase, thus the term "crankcase evacuation". This is something that would not pass a smog emmisions test with, if you live in an area where tailpipe emissions are checked. It's intended for race cars.
This picture isn't the best to show this system, but you can see the black 5/8ths heater hose coming off of the valve cover on its way down to the fitting on the header collector.
