I've had a lot of experience racing the Z06 against similiar cars and I also have experience racing against ESS M3's...
I put the ESS blown M3 with DCT in the category of a C6 Z06 with headers, exhaust, intake, and tune. Above 155 or so the M3 might pull it because of the Z06's long and weak 5th gear. If the Z06 driver really can drive he may lead the M3 a bit too though and then it would be catchup for the M3. Bolt on and tune Z06's can make around 500whp. They are extremely light compared to the M3 and the only disadvantage they have is the top end gearing and stick shift.
his: _______________ hers: Mitsubishi Evolution X
gone: R35 GT-R,C6 Z06, V2 CTS-V, E60 M5 SMG, CLK500