The TVR is not stronger than the Viper. It has about 50 less horsepower but is also quite a bit lighter.
The biggest problem with American supercars like the Viper and the Corvette is the fact that both weigh over 3000 pounds and yet still only have room for two people. The highest performance Corvette Z06 (405 hp) has an aluminum engine block, aluminum suspension bits, titanium springs, a hollow camshaft and still weighs in at a portly 3116 pounds. The Viper GTS Coupe (500 hp) is worse yet. It has an aluminum engine block as well and still tips the scales at 3460 pounds. Thats about the same as a full size Chevy short bed pickup. The TVR Cerbera 4.5 (450 hp) weighs in at 2425 pounds. That's more than half a ton of advantage over the Viper. There's no way the Viper can keep up with that much excess weight.