i would do the supercharged 6.4
but IMHO the charisma of the "10" is derived from the Viper V-10. kind of makes it.
and i am sure with the advances you could make a ram with the new 6.4 keep up just fine and fast enough, but could you imagine them with the Gen 4's.
WOW. bada$$.
You can't really mod the Gen4's because of all the computers and shit... can't tune it. That's why you haven't seen many boosted Gen4's If I remember right, there are 2 companies that make tuners for it, and they're CRAZY expensive.
The 6.1 or 6.4 can be modded to hell and back cheap compared to the 10.