Yeah handling probably can't keep up with that power.
I got some prep done today. I played with my C5Z, C6 GS and C6Z. The C5Z is pretty decent, I think it ended up with 450+ HP, 1st tire upgrade, and of course full suspension + brakes. The Corvettes have such tall gearing stock that you have to at least get the adjustable final gear ratio, if not the fully adjustable tranny (but that eats up a good amount of PI).
Still, I liked the C6 GS better. It too is close to 500HP and handles better than the C5Z for me. More stable and planted, with about the same accel I believe.
Maybe I was just expecting too much of the C6Z, but I didn't like it for A600. Very little room to upgrade meant you could have a hair more power, tires to make it actually competitive, or adjustable gears so you aren't lugging it up a hill in 4th, but you can only pick 2.
I'm going to try a couple German or Italian cars tomorrow, but I like the C6 GS quite a bit.