Assuming you get wheels that don't weigh a ton, one functional factor to consider is the overall diameter of your new tires/wheels. If you don't stay close to the right ratio front and rear (the ratio is in the wheels faq) then you'll have to turn off TCS to keep it from interfering. Also, getting rear tires that have a different overall diameter than stock will change your gearing. I can feel the torque difference between 255/40-17 and 275/40-17, which differ in diameter by around 3/4 inch. I mainly notice the difference on road courses where getting out of corners is slightly affected due to the taller gearing.
