I am very tempted to make a CD which demonstrates listening to an engine to determine how well it is adjusted.
It sems that this most important part of tuning is simply an unknown art for those with "problem engines".
Maybe if I set it to rap stuff - it will sell ---
I have never been able to tune an engine by any fu--in chart or a tachometer.
The tach reads the results -- that's all.
For you entry level guys - --get with some old fart who can show you what to listen for - it will save you much time and money .