Is there one over-riding factor that makes good squealy pinched harmonics easier to pull off? I am sure technique, set up, strings, gauge, pick ups, amp, eq, etc...are all contributing factors .......but the main factor?? I have 5 guitars at home: LTD, ESP, BC Rich, Ibanez and Traveller: some squeal easier than others, some are real difficult to get a good pinched H out of...??????