Sorry to butt in and knowing Karlos knows a fair bit but I adjust my mixture and can say it does affect the rpm range. If this weren't the case I would continue being leaner on boost and it's amazing what you can tell by smell,sound,state of plugs. I've done my own adjusting since 2008 and even when at a tuner all they did was make sure enough fuel at base idle,spark/timing and adjust boost accordingly. Then told never to touch the magnet fuel block on the side as this upset the whole running.

I'm just curious and not doubting. More to the point if what I've been doing all these years has been wrong how comes it runs spot on when taken to a tuner. Confused.com