To do testing of new car products, the owner of Mr Landcruiser measures car performance before and after a new product is fitted. Mr Landcruiser is testing the new 3 inch exhaust product. For a random sample of 5 Landcruiser's, the horse power is shown before and after the exhaust is fitted:

Use a 5% level of significance to test the claim that the average horse power has increased with the new exhaust.