I have a 08 G37 with a Stillen exhaust and Stillen Gen 3 intake. While it is a fantastic car, it is no M3. With the intake and exhaust i can keep up with a 335i, barely. I always drop behind slightly. There is no way it can beat an E9x M3, especially past about 40mph...
I'm looking forward to the M3 in 1 week!