Hi, I recentlly just put in a set of ATE power disk( I think they only make front rotor for 300E)and Mintex Brake pads from Bekker import. They are not very good, similar to the factory rotor and pads. In my opinion, if what you looking for is excellent barkes go for brembo brake system. If you don't really want to spend big bucks you can try the brembo cross drill rotors and ferodo pads. Stainstell brake lines never try that before. Another thing about the brakes. You should use better brake fuilds with higher temp, and DOT 4.
For handling I use koni shocks and H&R springs, but I talk to others, they all recommand eibach springs, and Bilstein shocks. Tires ? There are a lot of other selection besides Michelin Pilot tires. You might want to check out some of the tire test results on the tire rack offical website . Pirelli makes pretty good tires, like the P-Zeros, others like dunlop, bridgestone also makes excellent tires.
I think you should think about changing the sway bar, putting on a tower, struct bar etc..
By the way I think you should post this on the performance. That way you will receive more valuable advises.
hope this help