I was speaking to one of the Sling people at Oshkosh, and the TSi demonstrator has the port right behind the NACA duct.
He mentioned that they were going to move it to the rear of the aircraft, since the forward position does not read as well as the aft position.
I guess I'll be mounting mine at the rear, even though I liked the simplicity of just having them behind the instrument panel.
It seems like either position has its drawbacks.