Before my brother bought his Grand Cherokee SRT8, he was at the Viper Owner's meet in Las Vegas. They had all of the SRT packages available for the Viper owners to test drive.
The engineers admitted to my brother that they have to limit the power outlet of the SRT Hemis in the cars because the drivetrain cannot handle it. Only the Jeep axles were strong enough to handle the full output, so that's why he went with the Jeep....