i have a 2007 cobalt ss and it seems the z1 is about hal an inch to long for the hole does anyone else notice that its bigger?

The Z1 is a standart DD size. No bigger, no smaller.

Is it too deep, as in the back of the radio hits something in the dash?

Or is it too wide? Your car may not be compatible with aftermarket radio's if the dash opening is not wide enough.