Does Porsche Know More Than We Think?

Hello, I'm a new member here and a relatively new owner of my first Porsche a new- to -me 1999 Boxster. Like many driving enthusiasts I started looking a mods for my car to increase performance and have read many of the posts regarding intake, exhaust and chip mods to boost torque and HP. My mechanic is a Fabspeed dealer and wants me to install an exhaust system and cold air intake at a cost of around $2,600 with a claimed HP increase of about 20 HP. At first I was excited about increasing my modest 201 HP Box to 220 HP but started doing some research and have come away with mixed feelings about all the claims for these mods. For instance the PCA techs take the position that exhaust mods are a waste of money unless you want to spend it on a cool sound, which to me would be a waste of money as I already like the sound of my Box and don't want more resonance in the cab while I'm driving. Air intake mods have also been brought into question by one web site that did an extensive test on air filters and showed the filters used on the cold air intake systems allow more particulates into the engine causing increased wear and no HP increase near what is claimed. I don't know anything yet about chip mods as I've just recently become aware of them and have nothing to compare them to. After all the reading I've done, frankly, I've come away with the conclusion that the German engineers knew what they were doing and most, if not all, of these mods are a waste of money. I also know it is difficult for people who have spent money on something to admit that it was a waste so that has to be considered as well. What are your thoughts on the subject of performance mods? Have you installed any that you would sincerely recommend that have increased HP and torque that was proven to you and not just "it sure felt like it had more HP."