I think that being able to exchange upgrade kits for illegal boosters would be a useful feature in the game. Here's what I would suggest for exchange prices: (double the price seems fair too) 20 engine kits = 1 race fuel 20 tire kits = 1 illegal tires 20 nitrous oxide kits = 1 extra bottle 10 transmission kits and 10 weight reduction kits = 1 delay box I hope you will consider this update and I figured that they should be a little expensive scince they are a little hard to get by other means.