That's the point: every motor is developed with different emissions pressures from regulatory, but also cost directives from project development. The M56 SULEV aluminum intake with built-in CCV was way more expensive to design and manufacture than the plastic tube octopus calamity M54 got. There has to have been a reason they did not put M56 SULEV intake into service before. Perhaps it was only cost. The tube monster isn't reliable, so it wasn't that either. I believe most of these choices are based on cost.

But there was incentive to get SULEV certification later, so that warranted the extra cost of designing and casting that intake manifold. Also recall there were fires caused by the worthless CCV in M54, and that lead to an unsuccessful class action wherein BMW denied responsibility but updated the parts and issued TSBs.

Copying another OEM system is about using OEM parts that have been put into service by the factory for factory spec, which you know has at least had a minimum of thought put around reliability and liability. Minimum, obviously, as M54 CCV was a catastrophe.

After watching all posts by "mlody" and his youtube videos. it took me weeks and hundreds of hours of research on the piston rings and vacuum issues, I have come to the conclusions that:

1. Piston oil rings are worn (see "mlody" videos and website), allowing oil to be sucked into combustion chamber. Interestingly "mlody" never did the CCV Mod, instead he replaced his CCV a few times but never did the CCV Mod. He ended up rebuilding his engine with new piston rings using a mix of rings from M52 and M52TU engines.

2. Very few of us have the time/desire to replace the piston rings, thus the CCV Mod. The CCV Mod will definitely increase the vacuum a bit: it is somewhere between minimal vacuum (factory spec) and full (which is around 18 inches of Hg). I will do vacuum measurement on my CCV Mod system soon and post the findings.

This CCV Mod is not a permanent solution, rather, it is a "stop-gap" measure, which is good enough for me.

I was attacking the Valve Cover and the Oil Filter Housing Gasket on my 2003 BMW X5 5 speed manual this week and figured it was a good time to eliminate the factory CCV it was extremely easy but I do plan on adding catch can at some point.

Where exactly is a description of "catch can". Thanks

UPDATE.

See the photos of my setup in Post #164.
Now 1000 miles later, zero oil consumption.
This is a great mod, highly recommended.

Where the heck are you guys finding the little plastic plugs like the one used to plug the black plastic air distribution runner? I went to Autozone, Advance and Harbor Freight and found nothing. Plenty of vacuum caps, which would work for the dipstick tube, but that isn't going to work to plug the hole. Frankly, I'm tired of running all over town...

If you go through the subsequent posts by the O.P. (BavarianE39), he now uses that port that he used to plug it up.
It is better that way as crank case blow-by vapor is sucked into BOTH ports.

So, see my photos above and buy the copper "Tee" as mentioned.
Plus you need a short section of 5/8" or 3/4" hose.
See the photos in Post #164 above.

FYI, after 15,000 miles on this mod, I'm considering going back to CCV (though it's a sucky diy). The (assumed original) VCG developed a leak almost immediately after this mod. I replaced with Victor Reinz, and it blew again after about 10k. At this point, it's leaking like crazy. It's questionable whether VR gaskets are any good on M54, so maybe that's the issue.

I did recently replace the PCV (the replaced PCV seemed fine), and will replace the VCG again after carefully inspecting the VC for cracks. I may also take off the intake runner to make sure nothing's plugged. It's really acting plugged now; I *suspect* it pumped out 1 quart of oil after 15 miles of highway driving. Wife was driving; she said the X3 was billowing white smoke after she parked and appeared on fire. It was "really embarrasing" (sorry Honey!) It sounded like the PCV system might be plugged and some of the oil pumped into the valve tray was forced out the cracked VCG. I ordered a cold weather CCV kit but will first replace the VCG with Elring and see how long it lasts as a test.

My timeline:
10/11/2005 116k bypassed failed CCV with PCV mod
11/21/2005 117k new VCG (VR)
04/17/2016 120k replaced both front (p1) O2 sensors due to codes
03/01/2017 129k bad VCG leak noticed
03/05/2017 129k replaced PCV valve; original appeared OK
03/14/2017 131k very bad VCG leak; O2 b1p1 failed with P0131 (low voltage)

Will check PCV system for clogs, replace VCG again and keep another onhand in case. Thoughts welcome, and I will report back with results. Hopefully this is just a bad VCG because I love the mod, but I'm concerned about the lack of drainage to the oil pan may be causing pressure issues.

The GREAT news is no codes were thrown (besides O2 sensors) for 15k miles after this mod so far.

Valve Cover Gasket ---> BMW OEM only!