Cold air intakes have been an interest of mine for a long time. I have installed them in several cars, including my last ride a bimmer and even had the ecu reprogrammed to make better use of the cold dense air. IMHO the effects of these system is dubious at best, heat shields can and probably will cut down on the air flow. I have a 99 C280, i replaced the stock filter with a K&N, then disconnected the battery for 15 min, this is suppose to reset your cpu back to default, but keep in mind according to what model you drive your power window, sunroof synchro get screwed up also the ASP is so equipped also needs to be reset. Back to the filter. My C280's air horn is mounted into the front next to the right headlight and it's a short trip to the airbox. I noticed a slight seat of the pants performance increase with the K&N after a few days of driving and considering how the intake horn is set up with the air box, you can't get much colder air then that. Almost forgot I did notice a increase in fuel economy about 1 to 3 mpg according to how far, fast, and traffic was. But lets face it if it is 95 degrees outside, your going to get 95 degree air into your intake. Tne better plan is to increase the air flow to the TB and that's what the K&N does well. According what type of car your driving and the length and location of the air horn, wrap a piece of insulationaround the horn, foil type and tape it secure, get a K&N replacement filter, you just built a CAI.

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Al Lueb
1999 C280 54K miles
1979 450 SLC 144K miles