Well to be honest with all the deals around for cars already upgraded, you're MUCH better off getting one already built vs's going cheaper for stock THEN trying to upgrade it.
I'm not going to lie, Vipers are fun cars BUT you get used to the stock power pretty quick and a month later you're looking for upgrades. Saving the extra $$$ to get one off the bat is the way to go because you simply adjust the boost levels as your learning curve increases with seat time.
I remember the first time I drove around a friends built up DLM supercharged GTS then went back to drivng my bolt on Durango. Man alive my foot was ALWAYS to the floor trying to duplicate the feel of the Viper and of course not coming close.

And turbo Vipers are something else completely, they'll pull your cheeks around the back side of your head with enough boost on tap. :jester: