Happy to hear you’re having success with your 45 XP.
Check out this topic about voltage. Should answer lots of your questions.
As far as speeds I try to run book speeds if possible.
If you’re north of 300 in per minute you’re going to have to start dialing back your amperage and you will no longer be on hypertherms cut charts so if you find good settings in this range write them down for yourself. Or better yet share them with everyone else.
The minimum I’ve ever been able to do for Pierce delay is 0.4 if anyone else has been able to dial it down to 0.2 please let us know how.