Having watched other super sports cars go super fast on Michelin Pilot Sport Cup tires – MT cites the Chevrolet Corvette ZR1 as the prime example – SRT is looking to Pirelli for a set of rubber that improves on the Viper's P-Zero Corsas. Where the Viper ACR will be restrained is its power-to-weight ratio; rumor is that bosses at parent company Fiat have decreed that the Viper cannot outdo the 5.2-pounds-per-horsepower of the Ferrari F12 Berlinetta. It's also rumored that Ferrari doesn't want the Viper to have more power than the 731 horsepower of the F12, even though SRT has said it would be "relatively easy" to increase output from the current 640 hp.
The last Viper ACR didn't get more oomph under the hood, so there should be plenty of ways to navigate Ferrari sensitivities. However, the last Viper club racer did offer a Hardcore Package that dropped weight by 40 pounds. If the specific power-to-weight number really is a bright line for the coupe's development, it will be interesting to see if such a package is offered again and how SRT manages it.
UPDATE: SRT boss Ralph Gilles has poo-pooed these reports, saying that the whole thing stemmed from a "joke I made at the [New York Auto Show] Viper reveal ... that apparently took a life of its own," and tweeted that "Ferrari plays in a totally different market."