We all see this going back and forth. My 2 cents...all these answers are knowledge and testimonies to help people make the decision they can afford and are willing to make. If moving the springs around gets a few RPM fine. Gopowersports sells a air cleaner/pipe and jet for like $80 that perked my motor up. I played with the spring mod But only got like 4.2k on the tack. IMHO, to go any further, in for a penny/in for a pound just buy the ARC rod n flywheel and carb.
Now the governor is your foot and your ear.
Old story, I got a bigger motor, my tranny gave out, I got a better tranny my rear end gave out...I put in a HD rear end and I twisted the drive shaft......the moral: at some point....in for a penny/in for a pound.