The restrictor plate is between the carb and the cylinder. It is part of the cylinder its self. If you,pull the car you can't miss it. Rejetting the carb is a must if you decide to get rid of it. I believe a 65 main jet is what was put in. I have also seen it taken out in steps to add a little more speed as the kids got better at riding. The little motors can really move if do right.