Tie

I'm not much on U Tube videos for analizing sound of engines running as the recording capability and then my playing the sound over cheap PC moniter speakers don't do it justice----------but I will tell you what the change of the exhaust sound is the result of (in my opinion) and its hard for me to be forward and state this as the info about what is on your set up is difficult to believe ( I am not saying your fibbing) because I can't see it and you haven't proven it--------the sound change that your hearing is coming as a result of changing timing and mixture complicated by tuning length of exhaust headers as they reach tuned rpm length and same as you back out of it.

On a small block chevy, if the builder used roller rockers, he probably also upgraded the entire valve train to where it should easily be capable of 7000+ rpms------again , as your talking 5000 rpm I think some timing curve, carb tuning and utilizing tune length of the exhaust should make things sound better and rip on up to a much higher number.