I can't see that the passenger's side could have any function at all. The engine heat can not get to it. On the driver's side, it might help to vent heat out of the little opening where the firewall meets the fenderwell. If this is the case, then KB should build a plastic duct to route it directly to the side vent. This duct would also protect the inner fender from salt and dirt in the winter. The reason that there is a stock plastic liner in the fender well is to keep salt and mud from rusting the fender and body. By putting an aftermarket vent in there, salt and dirt will accumulate; causing the fender and the area around the doors to go to crap. Also, (if I remember correctly) there is an electronic module right behind that vent that might get wet. This is not a good thing. If the right side vent serves no purpose, then I would just paint the area black instead of cutting it out.
As for the vent screening material, either be absolutely sure it is painted VERY well, or switch to a stainless steel fabric. Seeing how you drive in the winter, if salt gets on it, it will rust. ALL of my Saleen screens are now a crappy shade or red. (RUST!) I purchased some stainless steel screens, but I have to rip everything back off to get them on.
One mod that "might" serve the same purpose as your vent is reverse hood scoops on both sides of the hood just in front of the windshield. These could be low-lying small scoops turned backwards to help pull heat out of the engine bay. If a manufacturer built these, they could also incorporate a RPM shift light into the driver's side scoop. The potential pitfall to these is that it might ruin the structural integrity of the hood. I have seen some Cobra cowl-type hoods with vents in the cowl.
I am not knocking your vents; just chatting a little bit about ideas that might make them better. It is always great to see new products. We just have to be a little careful about "side effects" until they have been used for awhile. Keep us posted.
Oh, one other thing; did you paint the bare metal of the fender after you cut them? If not, expect rust. Also, did they use stainless steel screws? If not, expect rust. I know, I sound paranoid. I am. I live in a salt zone in the winter. Many years ago I had to sell a nice 1973 Mach I because it just rusted away to nothing. Yup, paranoid would be right on.