This car is a momentum car. Early(ier) apexing is key to keeping momentum. That said, the first thing one can do to adjust the car without purchasing parts is an alignment. Late apexing usually benefits heavier, understeering cars which put down a lot of power/torque- allowing basically a hole shot drag race from turn to turn.

Watch these vids where I'm turning in sooner (for the most part) than the cars I'm following which meet the late apexing description mentioned above:

http://www.youtube.com/watch?v=J_cScMYKVlE (C55 AMG)
http://www.youtube.com/watch?v=YbhTyGYklY8 (350Z)
http://www.youtube.com/watch?v=34nH4I37sh8 (WS6)
http://www.youtube.com/watch?v=byc7F9fvtIk (350Z)

Read the alignment sticky on the top of the competition forum. Yes, sit through and read all the pages if you want to understand what your alignment should be, for the application in mind.

The strong point of the stock suspension is the double A-arm design up front, which dials in dynamic camber while turning, and the rear suspension which simply puts down a contact patch as well as it can.
The car, in stock form, will understeer a bit, yet it can be coaxed into power on oversteer, lift throttle oversteer, and it can be trail braked. A performance alignment will make it less prone to understeer at turn-in, and will allow for more precise trail braking.
The beauty of the car is that it will compose itself quickly after you stop making any illwitted steering and throttle inputs. It defaults back in to straight and settled (I've learned this the hard way).

What I found was that the car, was indeed underdamped and undersprung (mostly underdamped). Koni SA's go a long way to curing that problem plus they allow for adjustability for front/rear to dial the car in to your tastes. I chose Tein H-Tech springs to retain streetable comfort and clearance (important for me), while offering a slight increase in stiffness over the OEM springs. My car is a street/track compromise car down to the choice of tire and brake pad compound, yet it keeps up with more prepared cars at the track thanks to it being dialed in to my liking and because the driver is slowly getting quicker and quicker with more seat time and education.

Good luck.