Bummer.
I did notice that you run a full top deck. Since you are on asphalt, at least flip it over and use button head screws instead of the countersinks. Leave the forward most rear screws off the car.
For extra flex look at the top deck of my car in the pictures. I cut the rear cross member and the front as well. This should aid on your lower grip days.
I run my car this way on our high grip treated asphalt track too.
Also, post your set-up so that I can check it out and offer some suggestions.