Glad you're liking it - it's really just coincidence that there are two builds the same. When I first built up a car for the flowing tracks I first added all the tyre upgrades I could, then reduced the weight. As that took me just over the A850 PI limit (856 I think it was), I tried adjusting the tyres as you can move in smaller increments with those than the weight. I could have stuck with the Avons and reduced the width slightly, but I decided to go with the full fat tyres and drop down to Kumhos.
If you want to find the high downforce car's natural home, I would suggest looking at the Test tracks. It ended up between about 100th and 300th on all of them apart from Copperhead.