hey up,i am the man who made the flange adapter and the tube,if the turbo has a 3 inch housing and the adapter fits right up to that housing,then there is only 10mm of tube which is 3 inch then it goes into 3 1/2,if it was flowing the other way then a taper on the tube would of worked better,it is fiiting to a t4 turbo,so we are using the standard flange,thanx for your comment,i will keep it in mind when im making custom parts no one else is making