The Viper was on CNBC's list of top 10 most collectable modern day cars that will go up in value as future classics. Know what else was on that list? McLaren F1, Bugatti Veyron, Porsche Carrera GT, Ford GT, Mercedes McLaren SLR, Lamborghini Reventon, Ferrari Enzo, Ferrari F40, and Corvette ZR1. Not bad company to be in at all! Several of these have already been appreciating in value and most have been holding their own very well, and I have noticed Low mileage pristine Viper GTS models especially in a couple specific color combos and years selling for relatively big bucks at or close to their original selling price. The RT10 doesn't seem to have held it's value quite as well as they were more common, but that will improve as time goes on too. I expect the Gen 4 Viper to also hold its value better than the Gen 3 due to the sizable increase in power, updated hood, and rarity of Gen IV as opposed to Gen III models. I think Vipers are rarer than most people think even with the production numers being as low as they are. I believe there is a statistic that about 38% of new Vipers were wrecked within the first couple months of ownership, and I wonder how many were wrecked altogether...?
Not sure how much a heavily modded Viper would be worth as typically modifications don't return their investment future sales and can in some cases even be worth less than the same car that is stock especially if it was used on the track. However, if it was done by say Hennessey or a major shop like that and partially rebranded as such, that would likely help add to the value and history of the car as opposed to a car that was done piecemeal by the owner or a local shop. True Hennessey Vipers tend to command top dollar just as Rousch, Saleen, or Shelby Mustangs will hold their value better as time goes on as well. I had a Camaro as the very first car that I ever bought when I was in college (worked 3 jobs as a full time student at Rutgers to pay for college tuition and save for that car) and paid $7,000 for it used. Put nearly $18k worth of mods on the car, mostly to the engine, and sold it 3 years later for $8,000. the Viper is a very different animal, but I still don't think the mods add too much for the reasons I mentioned above.
I bought my 2008 Viper for many reasons. First of all, I have been dreaming about owning a Viper since I was 12 years old and saw my first one on the showroom floor in 1992, and had promised myself that one day I would get it as it was my "dream car". Secondly, I waited and found what I consider to be the best and most collectable color combo (apparently mine is one of only 9 verts made in GTS blue with silver stripes) with only 1,800 miles on it, and planned to enjoy it as functional artwork that I would take to car shows and the occassional fun drive on highways and back roads, but mostly keep it pristine and perfectly maintained for down the road. As of now I don't ever see myself selling it, but I'm absolutely positive that values will begin to skyrocket in the next 10-20 years as it is the very last and most powerful of the real pure sports cars ever built new and allowed on the roads just like the old Shelby's of the 1960's before all the nannies were added to the car's electronics. Next I need to get another Viper in a more common color combo and with more mileage that I wouldn't feel guilty for driving more often or even tracking... So my honest opinion is that if you have a Viper and keep it pristine and with a clean Title, you can and will be sitting on something very valuable at some point down the road, especially if in a rare and desirable color combo...