The calculator provide a pretty close estimate -- but it is not an exact science. You may experience slightly different results on the track due to track conditions, gearing and tire size, clutch or convertor, and other differences with the car.
Hi Brent, you can get the shirts for $15.00 each, plus shipping. I cannot see shipping to be more that 5 or 10 bucks US Mail. The shirts are made by Gildan and are a great quality shirt and Gotta Get It Designs is the screen printer. Did you check out our ball caps? They are also $15 each plus shipping.