hey guys can anyone tell me how to calculate my mileage, i just dropped 1 tooth in the front and added 2 in the rear. I knew that my spedo would be off but so is my odometer. whats the math to find out how much i am really doing? also any suggestions on fender eliminators i want something that drops way back. I am looking at greggs customs for flushmounts and got an integrated in the rear along with an Arata pipe

Any help or pics would be greatly appreciated