A few comments on my new experience.
I followed the user's manual steps, which indicated to drain the oil with the undercover attached. Apparently this is not a good idea. The drain plug is big (17mm socket) and the oil cascades out, so much and fast that if your container has a lower tank and the liquid moves thru smaller holes, it could overflow.
The problem is that some oil splashes inside the cover and wets the heat resistant material on the in-side. I don't know what that is, looks like asbestos or similar, but it turns spongy and fragile when wet.
I suggest the undercover is removed before draining the oil.
I decided to install a K&N Filtercharger and see what to do about the much talked intake resonator. To my surprise the 2009 air box doesn't have a resonator and no connection whatsoever to the inside fender area; the flat scoop is the only air entrance. Maybe this is why I hear a whine so clearly during acceleration; no resonator should bring more turbo sound to the outside.
The scoop connection and entry hole to the box is square and with a downward flow. Found that a bit strange, any comments? The K&N filter fits nicely, although it's a lot thinner than the OEM and the pleat orientation is vertical instead of the OEM's horizontal. Any comments on these details? Is the orientation important?
I took sometime to look at the underside of the car, particularly at the exhaust system. I don't know the exact diameter, but it sure looks like more than 2 inches, and bends are completely smooth, no corrugation. It could be mandrel bent. This exhaust is beautiful, I wouldn't want to mess with it in the near future, although I read that a performance downpipe brings good results.