Today, I built my lower air box. The new HX cooler rendered the ZL1 version useless so, worked with some ABS Plastic, heat gun, and built it up in sections:
Worked out nice. Next weekend, I'll take off the bumper and do the upper part.
After doing the lower box, I notice an oil leak again, from the Mishimoto sandwich. This time, after I took off the filter, I checked the sandwich bolt torque, and sure enough, it was loose -- not dangerously loose, but enough that I'm sure it was the cause. Looks like every time I change the filter, I'm going to re-check the torque on the sandwich bolt -- just to be 100% sure.