I tried the challenge with the April 2017 Seasonal events. I used a Ford RS200 '84 set to 500PP with SM tires on all events. There were no changes made between events.
It's lucky that I got the slowest fields for this....
Used the SSR, not really a muscle car but a beautiful Chevy none-the-less 500 PP, SM, same settings between each race event. The stock 59:41 split for this FR pickup was maintained for an already fully weight reduced 1621Kg.
The Rainmasters was tough with the SSR but it was a great challenge 👍