Running an Evo IX with bolt-ons that is converted to SD for drivability - one of the best things I did to the car.

Car has an old MAF ETS intake with MAF deleted that then resulted in a fairly small K&N airfilter right behind the radiator fairly close to the turbo - not an ideal place for sucking cool air. Car also has an ETS intercooler and ETS standard route piping.

I added a 5" long 3" silicone hose with a turbo bellmouth http://www.bpi-us.com/filterkits.php and a largish K&N RU-3100 moving the intake as close to the the driver's side inner fender as possible - into a cooler area under the hood. The set-up provides an almost straight run into the turbo.

Initial butt-dyno impressions: Off boost throttle response feels definitely better and car is even more drivable off boost than before. Can't tell a difference once the turbo spools - though colder air should theoretically be helpful. Worthwhile for daily drivability. Makes car more enjoyable in traffic.