I did test fit this in the car with a WRX, NOT an STi..... because it will fit on an STi too. But the 02-05 WRX has drive by cable and the cruise control module is mounted on the passenger side strut tower (close to the turbo). So I had to make this fit for older WRX's.
There is plenty of room for guys running 18g/20g turbos and possibly even DOM XT turbos. Ill have a friend bring his Dom 3 with 3" inlet by to test fit it this week. Its currently out of his car.