Personnally, when I made the region changer mod a year ago, I've tried the r422 trick, jsut to see what it acutally does.
With a ntsc console flashed to PAL my screen flickered and was in black and white.
With a ntsc console flashed to PAL and R422-mod enabled, my screen was in black and white but wasn't flickering anymore.
Has I have no real PAL games I use a backup of Sonic Adventure that I've made (JUE patched).
The fact that the screen is in black and white means it's outputting PAL video (NTSC TV can't understand what's goin on witht he color). But the flickering screen means it's in 50hz, the stable screen means it's in 60hz.
I hope that little observation could help you
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