Pics of GLA and Hong Kong diffusers at wok:
55mm GLA diffuser(20psi-Concoa reg):
60mm GLA diffuser(20psi-Concoa reg):
HK diffuser(28psi-Victor reg). You can see this is not working properly:
I believe the reason for getting only 0.3-0.4 bps is that the HK diffuser is not good(the last two pics). And, out of three HK diffusers this is the one that "works" best.
55mm GLA diffuser(20psi-Concoa reg):

60mm GLA diffuser(20psi-Concoa reg):

HK diffuser(28psi-Victor reg). You can see this is not working properly:


I believe the reason for getting only 0.3-0.4 bps is that the HK diffuser is not good(the last two pics). And, out of three HK diffusers this is the one that "works" best.