Ted, Here's my email address--
barryinaz@outlook.com I'd like to stay in touch with you, this is my 1st C-4, I've owned 2 C-3's. Where did you find that pic, that's exactly what mine looks like, I beg to differ with you on the restrictive part, you did the vacuum test sitting still when the car is moving air is swirling under the hood and that plate is blocking the louvers. Having all the louvers exposed creates a turbulence of air as well as does the K&N when the car is moving, K&N filters can pass 30-40% more air than a paper filter. K&N filters work best above 1/2 throttle for performance but I found that even with normal driving my gas mileage has always improved using K&N. Again that shield was only added because a few idiots ran thru puddles too fast and slugged the intake with water and then probably sued GM, that air cleaner sits too low in the engine compartment and will pick up water from the road very easily. Hope to hear from you, Sincerely, Barry