For what its worth, i use the cr125 jetting app regularly. I find it to be highly accurate for sprint track racing, but have discovered (the hard way) that its suggested jettings are way too lean for big road-race circuits. It is still useful, as long as you understand its limitations. For large road-race tracks, i have found you need to add nearly 20 jet sizes (if it says 178, you need about a 198), otherwise a 100 mph piston stick is in your future. That being said, it is dead-on for about any size sprint track.