1) yes - at the current diffuser angle, I expect near maximum downforce due to the diffuser. I think an important note here is the bottom of the car is flat with my current suspension setup, so I'm getting no downforce due to body tilt. One of my aerodynamic sources emphasized that the diffuser's most important job is to "drive the underbody airflow." The 13 degreee angle is too steep and isn't the best angle for dowforce or efficiency.1) Interesting that it seems to have reduced aerodynamic lift. (right?)
2) The car is lowered, right? (so likely not an issue at stock height)
As a side note, by blocking the cooling flow under the car and through the wheelwells, I might be getting some front downforce due to the hood vent vs underbody flow. This is covered at the racelouvers website.
2) yes, the car is lowered and running performance wheels/tires.
I plan to adjust the fore/aft tilt to about 0.3 degrees by lowing the front 0.25" and raising the back 0.125". I might see a 10% increase in downforce ( see post #16)
I also plan to reduce the diffuser angle to improve the airflow. If the angle's too steep, the air will separate in the diffuser, effectively forcing a smaller angle. (see post #16)