Originally Posted by adamsclubs
Axis, the 3" duct is air tight. The gap you see in the picture has no impact.
I had tried a 4" ABS coupler (actually a 3" coupler with 3.5" ID), could not fit in the tight space.
Apex's mod is the best you can get with the stock box.
not to mention i tryed over 8 filters from local auto parts