I'm in Dallas and just bought the Z1 34 Row kit to be able to take it to the track. The 34 will be overkill for daily driving as I've only hit about 230 even on the hottest days. Nonetheless, I figure its always better to have too much cooling as I can always block it off.
I've seen the OPs using velcro to attach block-off plate, but I wanted something different. I went to Home Depot today and bought
J-channel used for mount mirrors for $10. Then I cut some
black foam board from Office Depot I had sitting around from another project that sits in the channel nicely and won't rattle around. Also very easy to cut in case I just want to partially block. Here's photos
with and
without