There are plenty of guys out there not using the HD diff but you have to be careful with how you drive the car with that much power as any wheel spinning will but a lot of stress on it. The HD diff is just added insurance against failure which even in itself wont keep problems from occuring and common sense is the best advice with any diff in these transmissions. I have seen stock non-HD differentials fail without any hard driving but with a ton of miles on them. Good service habbits and driving manors keep things alive longer. There is no real good answer to your question though, but if it was in my own car I would go with the HD diff if you are looking for those kind of numbers to the tire.
