For injection. Basically leak down is the amount of fuel that the barrel valve is sending to the port nozzles at idle.
A setting too high and the motor will run but it will be rich and on alcohol will take for ever to build heat up. too little and the motor will build heat fast.
For all the cars we have that have run mechanical injection (we have enderle pills) We start with a 110 pill and the leak down is 30-35% with no idle poppets (for alcohol) I have never run gas with the injector cars
Once that is set up we run the car in the shop see how fast it builds heat and see if it will go on the brake clean and adjust from there. Once you find a set up that your program likes right it down in case you start to have problems and make some changes . Then you can always go back to your starting point
Good luck