1. Synfast resolution effects :

pixwin = True
nsimu = 50
Blue : synfast(ns=128, lmax=3*128-1) => anafast(lmax=3*128-1)
Green : synfast(ns=256, lmax=3*256-1) => ud_grade(256->128) => anafast(lmax=3*128-1)
Magenta : synfast(ns=256, lmax=3*128-1 ) => ud_grade(256->128) => anafast(lmax=3*128-1)
Red : synfast(ns=128, lmax=4*128-1 ) => anafast(lmax=3*128-1)
Cyan : synfast(ns=128, lmax=10*128-1 ) => anafast(lmax=3*128-1)

Spectra are then all divided by pixwin(128)^2 then plotted :