I was reading an import mag. I seen an add for Apexi's new exhust system. It was duel cambered...untill you get into the loud pedal. Then it's got a valve that opens and it's an open exhust.
I'm sure you can goto the website to see if they have anything that'll fit a Viper.
I'm sure you can goto the website to see if they have anything that'll fit a Viper.