RE: General port timing guidelines?
Make sure you check the radio button for gasoline. Temp EGT is in kelvin, which is [K] = [°C] + 273.15.
Some people complain about this pipe calculator but its based on accepted pipe formulas. I think where those individuals went wrong is with the EGT.
A tuned pipe even if the dimensions are off will still make a lot more power than open exhaust port or muffler.