In lvl 39, if you place your shot just right above the top circle, just nudging it, so it pushes you all the way to the "here" sign, you will get it in 1 shot
About the heart rate upgrade... Its OK... but what about people who get seizures and heart attacks easily? One way to make things better but still keep the "screamer" is at the start, when about to play the game, ask whether the person has medical problems or something like that and then when they pick "yes" then remove the heart rate upgrade.
Love the game except 1 thing...
The Heart Rate upgrade... which reduces my rating to 3/5..
People may disagree but it probably should be removed. If that happens then its a 5/5.