Shvegel and Tyler you both make sense. My main reason for replacing the stock filter system was because of how big the whole thing is, I didn't realize that I was forcing it to suck heated air from the radiator and around the engine instead of cold air from the front of the car. I don't know how the air intake is on the Pagoda but the W111 has the intake right in front of the radiator behind the grille. This weekend I put back the stock filter and what I hated most, the annoying hissing is gone. Indeed I was restricting the idle air supply too, I had to screw it in almost a turn to bring down the idle.
After I will get a heat shield I will probably tackle the idle and the cold/warm start, which while they work, they are not consistent as I see on a lot of members here.
Thank you.