If using the stock turbo inlet hose, the hose inlet is 3 inch diameter.
So a 3 inch pipe and conical filter will fit there.
However, you are likely to find that hose to be torn at the bottom near the turbo end.
And if it isn't, it will be eventually.
So I used silicone elbows that are oil resistant.
The turbo inlet is 2.25" diameter.
My conical filter is 3" diameter.
I used a 2.25 to 2.5" 90 degree elbow, a 2.5" pipe, a 2.5 to 3" 90 deg elbow, and a 3" pipe.
There are several ways to do it.
All parts can be found here :
http://www.siliconeintakes.com/