I dont know what some of these guys are talking about but you can most definatley run with minimal changes and make the car work on both surfaces. The only parts I changed from asphalt to carpet was the spool to a diff and the springs . I changed the setup some but no other parts and was plenty fast on both surfaces. You dont absolutley need all the option parts such as low roll blocks and stuff unless you want them or plan on running at the highest level of competition and traction like the IIC. If you want to know what I did to make my asphalt car a good carpet car with minimal spending shoot me a pm.