suspension wise, the RSX-S will do better, it's quick, light weight, and good suspension set up.

The G35 has the power, but due to heavy weight, and the 03-04 standard only come in regular suspension, so it's not as good. If it's the newer one or the old one with the sport package, then it'd be awsome, if not better.

yes, I testdrove both. A friends RSX-S with Tein SS and a G35 stock standard. The RSX-S handled better. I guess because he lowered 2.5", and also had some other things as well such as struts bars, braces, and stuffs with better wheels and tires. Compared to an 04 G35 Auto with standard option and 17" wheels and regular tires.