The biggest feature in Viper version 1.1.0 is the ability to import Virus soundbanks! To use this feature you need to download the free Virus waveforms available on Viper's webpage:
HOW IT WORKS ?
Be aware that the conversion is not always 100% accurate due to Viper and the Virus TI being two different synths.
Viper has features that the Virus does not have and vice versa. But as long as a Virus TI patch uses the same parameters that Viper has, the conversion should be successful.