This is already dated news.
While the Vette can be fitted with updated Michelin Run Craps, Michelin has already released an even higher performance Pilot Super Sport conventional tire that approaches the performance of the current Cups.
These new tires in 19 and 20" sizes are already in the marketplace, and are lighter, faster, longer lasting, and newer technology than the previous Pilot Sport 2's.
Newer Vette is having the 5th and 6th gear ratios raised for additional fuel economy, while the Vipers are being lowered for better ring performance. (no more need to bump rev limiter).
Viper also runs larger rubber, and the last run of Viper X's came with 295 (up from 275) front tires to reduce understeer.
To me, the Viper still holds the edge.