Some are running a 26, though the hole shot would be the determining factor on a 26 instead of a 25. That calculates 70.4 MPH with the nubmers you have listed. So you are running fairly well. There wont be much more to gain on a 26. Probably only a MPH.If you can run a 27, then you could gain 2 MPH. Also try a Trophy in a 26. That also would give a little more than a 26 Tempest. BCB