I know I am going to get slammed for this, but if you look at the actual cost for the materials that go into a twin turbo setup, it is no where near the prices that tuners are charging. I have made my own TT setup for a C5 that I had before my SRT10 and it ended up costing less then $10k. It will help if you can TIG weld and have access to metal fab equipment.
Add up the parts and see for you self. Don't give me the line of crap about how much research went into developing these systems, anyone experienced with FI setups can build one, the Viper is no different then any other car, it actually has more room for a nice set of turbos then the C5. I think I am going to have to dust off my TIG welder