the head doesn't necessarily flow better, but the pattern is much better. it's like comparing the head on the 258 AMC six with the 4.0HO six. the 4.0 has a straight shot to the cylinder, while the 258 head goes around a 90* bend.
the 20R ports are a bit smaller than the 22R, but the 22R has a swirl ledge for less emissions(helps the mixture burn more evenly). however, a 20R head will boost your midrange torque and let you rev much higher. i missed the off-the-line grunt of my old 22R at first but learned to love the powerband. the intake manifold is a better design, has 4 nice long runners rather than 2 big ones that split halfway to the ports like the 22R.
