OFF the foot well, I need a nap. Your right about the turbulence and also the additional air the would have to go out the wheel areas.This is the main motivation, although I have to believe that venting out the top rather than dealing with the turbulence under the front clam would be beneficial.
If you wish to see less hot air in the footwells, then you need to reduce under front clip air pressure. This can also be achievd by letting some air into the wheel arch area as well as playing with the nostril panels..My reason was to get the hot air of the foot well and it does a good job at that. It was done to spare expense of purchasing a better piece as Mike Drew has posted and have it repainted. Someday.....
SPF is not the only one.............. the majority of them do not make a full dropped twin nostril panel. I have two that are half-depth, and one that I got fom Jay Cushman that is full depth. It is actually oversize so that you can trim it properly for your radiator/fan combination. It looks almost identical to the pic posted by Mike Drew.
The single nostril panels are different as well. Only a few companies produce the panel with a straight lip across the top seen on the original cars (MK1). Regards, Scott
Cushman Competition, Jay Cushman....one and the same.