I would like a sound upgrade to the cars, as well. For example, I love the sound of the Lexus LFA (without an exhaust upgrade), but was put off when I bought the three standard Pagani Zondas (not the LM). They sound identical, and I'm pretty sure they shouldn't in real life. That seemed lazy, to me.
I wouldn't get rid of all 800 standards, but there are far too many duplicates among them.