check in on the schumacher corner
thread for details.
speaking generally, carpet cars often use stiffer chassis plates, lower shock towers, and stiffer spring and oil combinations. the setups tend to have more castor and camber as well.
some folks think this is a must, but in my experience it's not. for some of the races last year, my car had a broken top deck on it (intentionally) and flexed like an asphalt car. i did alright at the big races. it's more about making the rest of the car complimentary to what chassis/top deck you choose to run. the mi3, out-of-the-box, builds up very, very stiff. you should not need much to run competitive laps with it. the lower front tower is nice so that you can run the carpet shells (bodies) w/o having it look like a monster truck.
now, head over to your new home ...