sir this Test was performed on a 1998 JZA80 Toyota Supra (2JZ-GTE) completely stock
as turbo engines can fully appreciate and take the full potential out of the filter element
a small white cloth was placed in front of the intake pipe creating a barrier in between the two
the mushroom yielded the least power gains and let in alot of dust particulate (in the course of the 24hrs of the experiment)
the only good thing was that the HKS mushroom was washable
the cone filter we get over here are mostly Chinese and taiwan made and are no good
im sure if a good APEXi power filter is used the difference will be felt greatly
These tests were performed under very strict supervision in Japan and the results are also confirmed in the states